I disagree with the thesis of this article. "Commodity Web Applications" underestimates the importance of getting details right. I voted it up, though, because I expect it to generate interesting discussion.
I thought the last statement summed up the thesis of the article quite well:
"It’s less about competing technology, and much more about competing user bases."
I happen to agree with this argument. It is PRECISELY the core reason why I always laugh when I read about the next "Digg killer".
If this thesis is correct, then the only way to create a "Digg killer" would be to build a community around a celebrity instead of around a technology. The technology is only an enabling factor, NOT the primary factor for social applications to become popular.
The focus on technology is misplaced when it comes to the viability of social applications.
