I doubt the comments here would ever descend to near YouTube levels. For one, trolls on this site are mercilessly modded into the negative, and quickly. The last time I tried to make a snarky comment just for the sake of snark, it got downmodded so fast that I just deleted it. This same comment would probably have hundreds of thumbs up on YouTube by now.

I changed all of my videos to moderated comments on YouTube, and I still receive completely inane ones every day, along with "thumbs up if ____" comments. These, again, would be modded into oblivion here.

Maybe I'm one of the unwelcome newbies that are changing this site for the worse (as I'm not involved in a startup), but I don't think this culture has anything to fear as far as quality dilution goes. Noisy, sure, but still high quality.