pg's said many times that they primarily look at the people rather than the idea. It probably wasn't (just) paperbuff that got them to the interview stage. Just sayin.
Well, it doesn't matter. Do you think it makes much sense to invest in people who decide to pitch an idea that is not even 2 days old? Or rather - in people who think it's acceptable to do that? Hm.
I don't disagree with you, I just think that YC is all about young energetic people willing to put the effort in, so pitching a 2 days old idea with passion is kind of showing off some energy !
I went through TechStars Seattle last year and now have the privilege of watching the 2011 class from up close, since my company has remained in the same co-working space.
Everyone says that ideas are bullshit, but there isn't anything much like watching the evolution of your own idea and that of nine of groups of peers. But, it wasn't really until this year, watching ten budding companies from the outside, that it became so hilariously apparent that no first time entrepreneur has any fucking clue what they are doing.
I've overheard some of the companies pitch half a dozen ideas in a single afternoon. At least one or two of these wildly off course teams are the ones who are showing promise of discovering deep insight into their respective markets. For some teams, bouncing around is simply part of the process.