Close, but no cigar.I'm not sure exactly what you're disagreeing with, but, OK.
If a YC service can keep people from wasting their time on bad ideas that would be incredibly valuable.
Yes, it would be priceless. But I doubt it can do anything of the sort.
The astounding thing is how hard it is for even experts (whatever that means in this context) to decide what's a good idea and what's a bad one. Larry and Sergey heard from an awful lot of smart people that yet another search engine was a bad idea. And, numerous failures heard from a lot of smart people that they were on the verge of something huge, if they'd just keep going six more months.
The founders are always too close to their own company to see if it's really viable.
That's absolutely true. But, you and I are almost certainly too far away. The only people who can really tell you are customers (even if they aren't paying you anything yet--the people you'd like to sell to), and even they're wrong a lot of the time, so you have to get a lot of them so the margin of error shrinks, and when they start giving you money voluntarily (or start telling their friends, if you have an ad-driven site, and traffic starts growing steadily), that's when you know you're on a reasonable path.
I don't see how anything we talk about here can prevent bad ideas or make truly good ones bubble to the top. Certainly, if you find it valuable to bounce early stage ideas off of smart people, it's got merit. But nothing we can do here is a substitute for real users, and unless your target market is "technology entrepreneurs who think Paul Graham is fly", that aint us. And, again, my point was that talking about things on the Internet feels like doing things...but it isn't getting you any closer to your goals.