Thing about Discord and Reddit is it's a lot easier to moderate and control the narrative. Take a look at some of the bullshit posts on Reddit and the official forums for reference. So naturally there's going to be a drive for developers to communicate on those platforms where they can be reasonably certain that they're on home ground.
^ This All the normies want to talk to the community managers and pretend they are friends. No real talk going to happen there.
That being said, if we're talking coh2.org specifically, yes, there's been a downtick in activity pretty much since the last Company of Heroes 2 balance patch.
A lot of the people that come here knew Coh3 was coming and stopped caring about Coh2. Once Coh3 was officially announced, there was no reason to come here and talk about Coh2. So the site dwindled down. Coh3 is not the best right now so there is nothing to talk about.
I still feel ORG is hands down the best place to chat Coh. The less normies/goons/donkeys we get here the better.