Just to clarify, we’re only talking about mainstream social media here, right?

Yes, most discussions of infinite scroll center around this use, and it's what this topic's focused on. I'm aware that other uses exist, but frankly I'm not terribly worried about that. Pagination is a perfectly viable alternative for most every case I can think of that infinite scroll is used in, especially when paired with a half-decent search system, so even if a clumsy blanket ban were applied I think we'd be fine.