Is YouTube doing it with small creators actually in mind? Who knows, other than them?

I am pretty confident in guessing that they are not doing it for selfless reasons. Imo the reason is that the less information they give the user, the more you are beholden to the algorithm choosing for you.

But depending how they hide it it actually might not just be users, but also companies that e.g. buy ads from them. The less information they get, the more they need to trust whatever metric google offers them