I agree advice varies greatly in value. Bad advice is worth less than zero because it obscures the good.
I think YC's advice is generally quite good. The thrust of my argument was that advice and connections are more commodities than most investors believe.
Naval Ravikant, a YC speaker, says to assume investors are mostly money, as does Marc Andreesen:
http://venturehacks.com/articles/dumb-money
http://blog.pmarca.com/2007/06/the_truth_about_1.html
"Odds are, nothing your VC does, no matter how helpful or well-intentioned, is going to tip the balance between success and failure."
Ironically, because you distribute a lot of advice freely in essays and events, and because YC's connections are high-profile enough to work outside YC, it's less necessary to join YC for them.
To me, the other entrepreneurs in YC are the biggest value-add and worth a premium. I don't argue YC should match angel terms, just come closer to them than 1/10th.
I mention all this because I'm a fan of YC and want to see it succeed. The #1 criticism I hear about YC is the terms.* Investing a bit more is a good way to address that and one that now seems feasible. Otherwise it remains an obstacle to some high-quality founders and a way the increasing number of incubators can compete with you.
To use a mixed metaphor, I know I'm preaching against the choir in the lion's den, so I expect skepticism. I intend it as a friendly perspective.
-Mark
* #2 is that YC ideas aren't "big" enough, but that's mainly a VC complaint and one I mostly disagree with, anyway.