I've noticed it too. If I didn't check in for a day there would be two page's worth of replies to go through in the race and Q&A sections. This is how I see it:
Facebook and alternatives take flight
Interest starts to fall as the hobby ages out
More and more users install ad blockers
Ad revenue starts to fall because of the above
Hosting costs don't go down, and may even increase due to board software licensing and photo hosting
Board gets more embedded ads to cover falling revenues
Increased advertisement leads to more ad blocker installs and users leaving
death spiral
Honestly, if a few of us started chipping in we could start reverse what is happening.
