Yes, agreed, I'm sorry, I wasn't saying one can't get in without prior contact, rather that it's either prior contact or an interview in some cases, so that people who report getting into a program "without an interview" may in fact have that prior contact count as their interview. I guess I would be pessimistic about getting in without either, that is just mentioning who one wants to work with in the application, never approaching anyone, and then despite no interview after applying, still get accepted. My guess is that the interview might be a way to avoid the whole informal and uneven prior contact process, like at U Chicago where they expressly tell people not to contact faculty, but seem to interview everyone they take.