The fact that they are implied to be capable of collecting emotional energy from the general populous means that Kriemheld Gretchen is likely not a once off payment but an investment that keeps on paying. Forever.
I might be wrong, but I thought that Kriemhild Gretchen was powerful enough to kill all life in the solar system within minutes, so its creation would be a one time payoff of grief. A
lot of grief, naturally, but (barring a Madokami style wish where she specifically absorbed the grief of every witch past, present, and future) unlikely to be equal to the total grief production of humanity over the course of tens of thousands of years.
Meguca generally aren't Kyubey's enemies when they're making wishes, and the ones that do have beef with him when they contract generally have better things to use the wish for than naked spite. Madoka's long-thought-out wish didn't include vengeance, just improving the system. I think Kazumi got a second wish because system-breaking shenanigans and didn't use it to hurt Kyubey. Sabrina hates the coobs exactly as much as the fandom does, but she didn't wish suffering on them.
It doesn't matter that most girls don't realize the enmity or don't act on it: as Homura displays in Rebellion, it only takes one girl to evict or enslave or destroy the entire incubator race for all time. Kyuubey is messing about with entities capable of reality warping wishes and magic, so he
really ought to be more careful about ensuring our goodwill, even if it does mean that the grief harvest would be less efficient. This is one area where the analogy of farming breaks down: humans have real leverage to use against the incubators if it comes to a fight (or a negotiation).
Any and all agreements with Kyubey have the issue of allying with a being that will betray us literally the moment it becomes profitable to do so...Trusting Kyubey in any long-term fashion can only end with the line "Curse your sudden but inevitable betrayal!".
It depends if the incubators really are as serious about telling the truth as they appear to be. If they are incapable of telling direct lies (or if it's repugnant enough that they wouldn't break their word just to obtain a little extra energy), then some sort of agreement should be possible as long as we're very careful about what we and they would be agreeing to. It's not necessarily the
best option (arranging for Sayaka to nuke them with a wish would be another option, for instance), but betrayal shouldn't be
inevitable.
The first thing to understand, is that witching out is responsible for 90-99% of the grief created by a magical girl over their lifetime. Under normal circumstances (i.e. no sabrina), Kyubey may well have the most efficient system.
We don't actually know what the numbers are for this. This is important information that we should ask Kyuubey about.
It would be considered the neighbourly thing to do, to hold a friends gem during times of distress and keep a seed pressed to it. With such a small risk of hatching, people would keep their gems in transparent, padded cases with the clear seed constantly in contact, so that no matter how they fuck up they wouldn't spiral. Witch outs would very much be the exception, not the rule, under these circumstances.
This might help prevent witchouts in cases of extreme emotional distress, so it's definitely worth looking into. But it wouldn't be 100% successful (when there isn't a grief seed available and no one around to help, for instance). And the longer that people live, the more opportunities they would have to witchout.
It's likely that more girls would die from gem destruction than from witch outs... Which would actually be a problem for the growing population. At 10 years down the line there would be more magical girls that grief seeds, so a system of sharing would have to emerge... at 20 years there would be closer to 40,000-200,000 meguca worldwide and a severe seed shortage shortage. An average city would have 60-300 meguca with only 10-30 seeds. At this point you might get two or more girls grief spiraling at once, with only one seed between them. Because lots of girls are friends a spiral of one could spread to others, leading to the dwarf fortress tantrum spiral, except it leaves a city with 1/4-3/4 of its meguca witched out. While a tragedy, this would form a self-regulating feedback loop which would slowly increase the number of seeds in circulation, keeping the ratio at just about the level required to cause quiet desperation. At 25 years this strategy become untenable as large groups of meguca fight over scarce clear seeds and gem destruction rises.
One way to avoid starvation when the population is heavily weighted towards meguca with very few witches would be to arrange for meguca to voluntarily put their bodies in stasis for a short time so that their soul gems can be used to cleanse others. This would allow an arbitrarily large population to survive without any witches at all as long as people are willing to go dormant every now and then. This would be a much better solution than familiar farming (unless, of course, we can farm familiars by directly adding grief rather than by allowing them to mature due to human deaths).
As an aside the possibility of familiar farming raises interesting ethical questions about meguca revival from seed form. If a witch is turned back into a magical girl, but it still has a familiar out there, and the familiar becomes a witch, and that witch is also revived, what happens? Do you get a clone of the magical girl? If one girl saved is good, is two better? Can the clones use magic? Does that imply we're also cloning the soul?
These are interesting questions. Ones that we really need to look into once we find a grief seed that came from a familiar which matured into a witch.
Point of order: It took Sayaka almost an entire week from the revelation of the lichbomb to her witching out, and that's with her purposefully neglecting the care of her soul gem and fighting two witches on top of that. A grief spiral isn't an instantaneous process, and baring extreme conditions it takes actual work to witch out. It's not like you are in danger of witching after ever bad event.
Sayaka's grief spiral can be looked at in a different way. The girl was (relatively) stable before she contracted. It
only took a week for her to spiral out of control to the point where she was willing to mutilate her body, break-up with her best friend, murder some jerks on a train, and witchout. This despite the fact that she had close friends and family who cared about her and tried to talk to her and a time-traveller who tried to prevent it. Grief spirals do show signs and there might be time to react in many situations, but they also appear to be extremely difficult to stop once they get going.
Another point: what about all of the witches that we have found so far who did not result from anyone we know witching out? Either they were generated spontaneously (somehow) or else they were familiars who matured or else they were girls (like Nagisa) who were contracted by Kyuubey but who witched out almost immediately afterward. Depending on the circumstances, grief spirals can happen
very quickly.
You've missed my point completely. Or we're both talking past each other, possibly. I'm literally saying that more witchouts over a shorter period, if applied universally and to a longer period, literally means more witchouts over a longer period. That's what makes pursuing immediate witchouts as a rule better than not pursuing. Situations like Madoka are the exception, not the norm.
Let's set aside Madoka for the moment and talk about the current situation where a certain number of meguca witchout due to grief spiral, others witchout due to hunger, and others have their gems destroyed due to conflict. In the short term, Kyuubey would benefit more by preventing us from cleansing because we would be preventing the witchouts that occur due to hunger. In the long term, however, cleansing would allow more meguca to survive (both from hunger and from gem destruction). As the number of meguca grow, the total number of witchouts could would also grow until the total number of witchouts exceeds the previous number, even if it's a smaller fraction of the total. To put it a different way: if Kyuubey collects grief from a girl witching out right now due to hunger, then he gains immediately, but if he waits a hundred years until that same girl witches out due to a grief spiral, then he gains the same amount of witchout grief plus all of the incidental grief from magic usage. And he would definitely collect more grief from girls who would otherwise have died due to soul gem destruction. That's what I mean by short-term gain vs. long-term gain.
I think grief seeds generate grief over time, so each seed is already giving off unlimited energy.
I don't think that this is the case, but we haven't verified it yet either way.