I would personally argue it's a large one, but it certainly IS one.
It's not about an attitude about life - I don't worry about gatekeepers at because practically you can't. You've got to give gatekeepers no choice - give YC no choice but to accept you, Techcrunch no choice but to write about you, etc. etc. But as a matter or discussing how our SOCIETY should work, gatekeepers need to examine their biases, strongly and often.
1. That's what YC almost always does, invest as the first and only investor in their own round where they take 7%-ish equity in exchange for a bit of money and all the other things they do. There are rare occasions where that's not what happens, but that's the norm. There's also a follow up from the YC fund that is convertible debt of some kind and always comes from the investors, but that's still 100% based on YC's decision
2. Gatekeeper might not be the perfect term, but it's darn close. YC is a gate, they are the keepers of the gate, and it's an important gate. Not the gate TO doing a startup but a gate IN startupdome.
Edited original comment to be more clear, I can see how the insinuation the being in YC is a gate you must cross to do a startup would cause confusion.
YC is one of those ways, arguably a very significant one.
If Google drops you from search-results, game over!
If YC accepts you, game on!