They're busy building stuff without blogging about it. It's tough to assess a change in culture when your heuristics are limited by selection bias favoring loud contributors over productive builders. That's not to say there aren't great hackers who blog; but there are certainly bloggers who are bad hackers, and by definition they're more immediately visible than great hackers who don't blog. I'm sure there is a term…
My take of this situation is that people are overworked, and community has become overly regulated, unrewarded, and suppressed. (Language/tone policing, spam, aggressive individuals encouraged in groups, bad group membership policies [CoCs used as bullying devices more than simple rules to follow], dev advocates stepping on everything)