As of your last point,the forum activity haven't actually dropped because using the LoyceV activity stat,
We went from
286k posts per week to
32k posts since 2018. That's a massive reduction.
For full raw Merit data, see
merit.all.txt. The number of Merit per post is a lot more than than it was in 2018. But there was much more ICO spam back then, so just post numbers don't show everything