Honestly, any section being a one chance only is pretty terrifying, not gonna lie. As said in another section here, I had one app come up for revisions in another game because the mod team felt something I had included wasn't true, and I just gave them the canon evidence for it and it was fine. If there had been a no revisions policy there, he'd never have gotten in. Unless the app team are masters of all canons, which they can't possibly be expected to be, there will almost always be something like that or similar that pops up.

Rejection is a crushing thing and pretty horrible to deal with when you really want to be a part of something. The chance that it could happen without any chance to fix something is enough to make people not want to deal with that possibility. Especially if you've had encounters with revision requests before! And with emailed/hidden apps, you're sailing blind to start with because you don't know how often revisions are asked for/rejections are handed out or what's often asked for to try and avoid those pitfalls before hand.