One thing that I'm getting out of this article and which I tend to agree with, if a site isn't focused on a specific community the way HN or StackOverflow are, there is a tipping point at which its quality becomes inverse-proportional to the size of the audience. Quora might still be good because it hasn't yet reached it.

eBay used to be good as well, then one day they got so big that buyers and sellers were practically left to settle their disputes on their own. eBay used to be my #1 stop for anything that I wanted to buy online. After getting burnt 2 or 3 times, I haven't opened a page on the site in over a year and haven't bought anything from it in the last 3.

I'm also going to make the bold claim that if Facebook was in its current state 3 or 4 years ago, in terms of quality and community, it would probably not have gotten the success it currently enjoys. Most of us would just consider it another MySpace or HI5 clone.

As far as Quora goes, if it is indeed successful, it might also very well be a victim of its own success, but maybe by then it will be financially viable, which is the one thing that matters most to its backers.