On a less joking topic, why is the potentialbomb so important to keep from Homura? Madoka's potential would be increasing loop after loop, I get that, but she's been targeted by Kyubey from the first timeline. If Homura's objective is not letting Madoka contract then it isn't much of a difference how much potential Madoka has if she's always seeked by Kyubey.
Probably I'm missing part of the picture here.
Homura's been stomped down all her life. She is a human being without that all-important thing that is self worth.
She doesn't consider herself human, she can't consider herself worthy of Madoka.
Of course she wants to feel she's worth
something, but she doesn't have any important experiences that would tell her so. Instead she's spent years bedridden at the mercy of others, and once she tried to do something by herself, she 'lost' her Soul and Walpurgisnacht blocked her every time.
So Homu does not have self worth.
What she's got is a mission to find her own self worth. She didn't Wish to revive Madoka, but to have a chance to protect Madoka instead. It is by protecting Madoka that Homura gets her own sense of self worth. But only if she succeeds.
The way I like to think about it is that Homura's
borrowing that sense that she's worth something from the future in which she accomplishes that goal. If she wins, then that means she's worth something, and if she doesn't lose, that means she'll win at
some point. So that self-worth is assured and valid for her to take upon herself.
Cue Potential Bomb. Introduce the fact that normal Madoka wasn't that important a target to Kyuubey, and that the whole reason why Kyuubey's been getting more and more insistent on targetting Madoka, the reason why Madoka's been in more and more danger, is Homura.
The longer she loops, the worse she affects Madoka. That "if she doesn't lose, that means she'll win at
some point" only works if there is no counterbalancing force, if looping has no negative effect.
And yes, at some point, Madoka's Potential would be big enough that it wouldn't matter from a rational point of view, but not from an emotional point of view, to someone who's close enough to the verge of suicide to be Witch bait.
Everything we admire about Homura stems from the self-promise that she will win because she has theorically infinite chances of winning, that as the chances she's got approach infinite, her hope of success approaches 1. If you even fudge that one bit by, say, introducing an opposing factor, such that there
is a cost to each loop, that they're not
free, then that
certainty is lost.
You can
rationalize that she would still win if she kept going on eternally, but it becomes a higher complexity problem such that you can't instinctively say "yeah, it doesn't matter".
Even if you could, Homura has to deal with the fact that it's she herself that's being this source of trouble for Madoka. Even if she would feel content with saving
one Madoka... she still would feel she was the one who caused so many Madokas to get targeted by Kyuubey, and die.
So, take away the certainty of victory that allows Homura to feel she's worth
something,
while turning it on its head so Homura feels her worth is a net negative.
The canon loop, once Homura's defeated by Walpurgisnacht again, she goes to turn the shield, thinks that she's just making things worse, and gives up and despairs.