Wikipedia reminds us that the term "social software" also arose in the late nineties to describe software emerging out of alliances between programmers and social groups whose particular kinds of cultural intelligence are locked out of mainstream software.

[from Wikipedia]
"In this understanding of the term, the social is understood to also have a political and aesthetic sense, not simply acting as a kind of glue for a collection of normatively understood 'agents' whose inter-relations are formatted by software. What both positions share is an understanding that particular design decisions and the grammar of interactions made possible by each piece of software is socially significant.

As the term has become more important to the computer industry, this earlier use of the term has often been edited out of memory."

Anyone seen Clay Shirky's Clay grid relating increasing community freedom on the X-axis and increasing annoyingness (suscepitiblity to common group problems) on the Y? The curve was steep and sudden. As freedom grows, so does trouble.

He proposes development of a pattern language - a tool adopted from architecture for describing issues and strategies or problems and solutions without being overcontrolled.

Anyone seen Clay Shirky's Clay grid relating increasing community freedom on the X-axis and increasing annoyingness (suscepitiblity to common group problems) on the Y? The curve was steep and sudden. As freedom grows, so does trouble.

He proposes development of a pattern language - a tool adopted from architecture for describing issues and strategies or problems and solutions without being overcontrolled.

The three reasons are spot-on. Passion is all too rarely mentioned as a driver, yet it's probably the key one.