I have been here for quite a long while and I've seen the engagement go down drastically especially in what I would call more "technical" topics. Maybe its because everyone from that era has grown up, heck even I don't get time now because of med school. Maybe its because newer members aren't as good as the ones from the 2009 era and before. I would coincide this with the fall in the PC gaming community that I've seen. When MBL servers still existed, there used to be an entire organized community for Team Fortress 2, Counter Strike Source etc but that has all but disappeared now. In that era there used to be multiple discussion boards, I remember WorldCall's own discussion board, Wild Cows Consume Kebabs (WCCK), MBL discussion board etc and all were highly active in those days. Now except for PG, all of them have faded away.
Heck even the PC Hardware community has all but faded away and the effects can be seen on the market. There used to be so many brands a few years ago, XFX, HIS, Gigabyte, ASRock, EVGA, MIS, Asus etc but now all you see is either Gigabyte or Asus because the demand is so low. The LGA 755 days were golden and the prime time for PG I would say.