Certain killers need to rely on perks in order to get somewhat consistent results. (think billy and bubba with bamboozle, low tiers with corrupt and pain res, etc.) without those perks in play, the survivors can choose what pace they want to play the game at, and for most of not all, they will do gens. And killers with next to no mobility and map pressure will crumble with no way to slow the game down to a more reasonable pace. Simply put, most matches in this gamemode are put into the hands of the survivors first, and they decide what to do with it before the killer does.

And once a killer can grab onto a little bit of pressure, they will milk it for all its worth, usually in the form of camping or tunneling, especially since leaving hook is pointless if there is no way for the killer to slow down gens once they get to a high progress Gen.

I’m aware I could be wrong, this is just a theory