It’s a form of self selection. YC (and silicon valley at large) isn't interested in founders with pesky things like real life responsibilities or anything else that will prevent them from focusing on their startup 24x7.
YC is so early on some of these deals that the primary gauge is team - which means personality of founders. Very hard to measure remotely.
I'm in a group, not as big or famous, that does early checks. We're 95% remote. IME, it's so hard to make those judgement calls through web-cam.
Agreed that founder focus is a big factor and that life gets in the way (of deals). However, if you don't like YC conditions there are 100s of other places to (attempt a) raise.
