I'm also surprised at the negativity. If you have an idea in isolation, that you haven't tried to validate yet, what evidence so you have that it's worthwhile? At the very least, YC has heard a lot of ideas and, presumably, are better at spotting the ones without potential. So, if you have a good enough team, they can coax ideas out of you and then steer you toward the best one. You probably have a good idea and just don't know it, possibly because of the "schlep" blinder that pg has talked about. I get the impression people are angry that they can't be mediocre and get in on the merit of their idea.