It's really sad, tens of thousands of founders wasting years of their career on the low-tier net-value-negative accelerators.
How bad could they be? Far worse than you'd imagine, as I've personally seen.
Before ViaWeb, PG wrote books [he wrote one afterwards too], and to me, YC has always been loosely modelled on how I imagine good book publishers work: experienced editors helping promising authors write interesting works on one side and a sausage factory facilitating printing and distribution on the other. Instead of books, YC publishes companies, but the structure of the founder-partner relationship seems grounded in the founder being the expert in their company and an acknowledgement of fallibility on the part of YC staff...there seems to be a belief in treating companies as a creative works [-1].
My impression from both distant and near contact is other accelerators [0] are missing that layer of abstraction [1]. There are many that get the startup industry mechanics, but few that seem to go through the really hard and non-obvious work of creating better policies. Part of the reason that I think YC was able to create a place with generative policies is that it started when its first partners felt ready. It could because it was early if not first. Other accelerators have been reactive...they raced to get into a fast moving industry and consequently tend to use the policies traditionally associated with the mechanism [2] at best and with small business in the middle case and flat out scams at worst.
If there's one last piece of the puzzle, it's that YC's early partners have tended to eschew celebrity to a reasonable degree...if not giving TED talks every year when you could is some measure of reasonableness. It might be called the "Robert Morris effect."
[-1]: PG's before YC was Hackers and Painters. In my mind not uncoincidentally.
[0]: Sorry, but that's the name of the industry you YC folks created
[1]: and some appear to miss the whole startup idea that taking a cut of each startup's funding as a fee reduces returns over the long run. Their policies are more akin to those of real-estate development where there can be underlying assets at liquidation or businesses where ROI comes from dividends and companies can be optimized around income tax as LLC's and S-corps.
[2]: The other day I wondered how Marc Andreesen would evaluate a company with a Netscapesque equity split among founders, these days.
It just seems more likely that one company has made an aberrant success out of a bad market than almost every other company has fumbled a good market.
I haven't been through an accelerator, happy to be shown where I'm wrong.
Also, don't underestimate HackerNews. How many other "accelerators" have a content hub that engages their customer base daily. You can't underestimate what that does for their brand.
Granted, these companies aren't soaring into the stratosphere yet. "Already working" can simply mean a few early customers, a functional and polished prototype, or even just a really good idea and a (very) proven team. The point is that YC, like any investor, tries to minimize risk as much as possible, even though they're in the riskiest layer of professional startup investing.
I used to agonize over the fact that I never worked at a big name-brand company and that I haven't been able to hobnob with apex talent who might co-found a startup with me as I figured that was the only way to get into YC or TS. This one bit of advice (i.e. traction is everything) washed away that anxiety like night and day. The ability to succeed is in the founders' hands, not YC's magic wand.
Doubly so... because do you really want to take investment (even from YC) in an idea that doesn't have traction and isn't working?
I think that's actually a very interesting question. It's certainly possible that the accelerators here encourage exits instead of world domination, because it's 'safer' to exit if you have the opportunity (i.e. why soldier on for an IPO when you can be acquired, the accelerator makes its money back, you make some money, and everyone in the region can say 'oh well startup x was sold, look at the success!'). Continuing on represents risk...the company may not IPO, or may not continue to grow at a rate that supports the valuation, etc.
I've not gone through an accelerator here in Pittsburgh (or anywhere else for that matter), but I would strongly suspect a large part of it is the cultural mindset here--an exit is a win, because compared to their peers, that's enough, just like how our high school football teams view winning the local championship as more important than winning states. Not saying that an exit isn't a win (it certainly is), but you don't see anyone around here swinging for the fences and taking that continued risk. My $.02.
Those startups need to work their way up, and naturally many of them don't make it.