So interesting that this post is about putting incentives in the right place.

I distinctly remember the number one fantastic thing about StackOverflow in the beginning was that their incentives were so much better than all the alternatives.

The way SO gave you points for answering questions and gave you more for being the best answer etc etc meant the answers you got there were so much better than anywhere else. This is why the site grew so rapidly and so quickly became the best place to get a great answer.