YCombinator has its biases, but I don't know of many other investment firms that have a university style, "application" process. It's almost always, warm-intros you need.
This Early access network is just an intro system once you get through the Application process (like Universities having a job fair).
Do not mistake any VC's eagerness to find fresh meat for the grinder for a philanthropic or otherwise virtuous motive. VC exists for one purpose only. Extract value from others.
Pretty much every incubator I've seen has an open application process.
TBF YC has always said the value is in the network.
What's interesting (alarming?) is them formalizing exclusion of access to technology via the network. It's explicitly ossifying an access control system over what used to be handshakes.