Instead of trying to define a guideline that says “may not use multicast for this, that, blah”, apps instead just have to request it and explain why. It’s probably not a topic that the usual review team can consider without extreme levels of training beyond what’s necessary, and it’s a specialty network skill with lots of privacy traps. It also allows Apple to see who doesn’t request the permission but uses multicast anyways, because they might be using some sort of framework that is unknowingly tracking people, and then they can identify and start rejecting that framework storewide.

“How can we ensure every request for multicast escalates to someone qualified to make a decision that we can stand behind?” An essay question is a great answer, even if people hate the uncertainty. Better that than a new guideline!