We'll get back to you, but likely not straight away, as fleshing out tactically-relevant worldbuilding is a delicate and spoon-consuming process.
I'd like to try and give a clearer outline of where we're coming from about this, since the disparity between what-players-know and what-QMs-know seems very salient to this example. No need to act on or respond to this immediately, I just want to help share context.
We don't know much about sealing arrays. There's been, I think, just the one quote describing them in any detail. Leaf either doesn't have any surviving examples or we never dug deep enough to find them. They were most likely used during the world wars, on missions of critical importance sufficient to justify the greater costs of the sub-discipline. I think the one example we heard of was a large defensive dome?
What this translates to, on our side, is a pretty large swath of unclearness about how strong they are, how difficult they are, how costly they are, etc. The only guiding star for this that we have is the general place of seal arrays in the world: the costs outweigh the benefits most of the time, and only in niche situations (like in world wars) do they find any use. That, to me, sounds like a tricky balance to manage, because it takes quite a lot of inconvenience to outweigh the draw of a more potent effect.
Our obvious point of comparison here is runes. Both runes and seal arrays are known for producing much more potent effects, at the cost of much more preparation ahead of time. A rune takes 12 hours to make, 3 if you're rushing, and can't be moved from its spot. Seal arrays, if they have hundreds of elements and each element takes 5 minutes to craft, would easily take tens of hours to prepare, and while they could be scribed at home the act of putting them all into place cannot be done mid-battle (unless you're Konan). It's not one-to-one, but the disciplines seem to be mirror images of each other in that regard: a comparable increase in cost, for a boost in power.
The concern ultimately stems from the following question: "what if the power boost is also comparable?" This last arc has made it pretty clear that, inconvenience or not, runes are incredibly powerful tools that will definitely see more than niche application. There's thus a concern about consistency: do seal arrays largely go unremarked if they have a similar level of power? We went through a world war of our own without the topic coming up, and it doesn't appear that Jiraiya researched any of his own. There's wiggle room still, but the fact that we haven't seen them by now after all the crazy events of the quest definitely points in the direction of "they really are niche after all". There's also a concern from tonal consistency: it doesn't feel like the power of runes would be quite so hyped if they were only marginally stronger than seal arrays. These are, ultimately, us fretting on your behalf, not actual objections so much as "what would I be worried about in your shoes?" but they are still what's been floating around my mind on the topic.
The part of me that thinks of worst-case scenarios imagines the following: seal arrays are nearly as powerful as runes, and as an established part of the setting nearly every major power in the world is well-used to using them. Now that their properties are pinned down properly, we can start to ask the question of when they should be used going forwards. Just like with runes, the answer quickly becomes "they're too useful to be ignored", and suddenly every other major power around starts throwing around rune-tier effects that they definitely always had but never felt the need to talk about until now. And on our end, all our time we spent as a sealmaster before arrays were a thing we could engage with, all the time we spent quietly ruling out that Leaf had any of its own, leaves us holding the bag with no arrays of our own and no way to get any since Leaf doesn't have any either. This is, of course, pretty unrealistic, since it runs contrary to both how niche arrays have been described as and how unprecedented runes have been depicted as, but it's still a frightening image: as if the rest of the world powerscaled up to match our runic effects.
While it is always within human nature to worry about such things even if they're unrealistic, I don't think we'd be this worried under ordinary circumstances. After all, there's no way seal arrays will
actually turn out to be that powerful, right? What tipped this over into more active worry was the recent ruling (now redacted) that Hazou believes the nature chakra ward could have been accomplished with a sealing array. If so, that would anchor the power of arrays pretty high. Really high, high enough that it'd be hard to argue they aren't as powerful as runes. There are, of course, other ways to look at it, like if it was the power of a hundred arrays all active at once, but it fed a trickle of doubt nonetheless, one that we're anxious to banish.
At the end of the day it's hard to say that we're not also motivated by simple concerns like "we want runecrafting to remain special" or "we don't want this tool that our enemies have but we don't to be strong". I do admit that I like runes wielding the most raw power in the setting by a mile, and that the idea of our foes being stronger only makes me worry more. I also do think that this will in the end shake out into something reasonable and simulationist, once enough time and energy has been directed to it to raise all the questions and iron out all the wrinkles. But it might be a rocky path to get there, and I hope that by sharing our perspective now we can make it smoother.