That's my bet. I've gotten away without asking any questions on stack overflow since its genesis. There's usually enough already asked on there that I can synthesize the answer or trigger an idea for something to try that ends up working.

Yeah, and I feel there's not much point contributing answers either, because it seems most situations are either:

1. Simple and quickly snapped up by other users who are aggressively trying to grow their reputation on the site (perhaps with more free-time than I) and there's a first-response advantage that crowds out later answers.

2. Duplicate of something else. Why bother making a good answer when it'll get closed because somebody else happens to think a different question is the "better" one?

3. Way outside my expertise and it's probably better for everyone involved if I don't try to answer when I'm not sure.

So in a way SO is a victim of its own success when it comes to lowered engagement.

P.S.: I've even had an answer I was proud of converted into a "community wiki" just for a few tiny wording changes, with the side-effect that I get no reputation from it. So yeah, it seems like a rat-race.