yea fh, fhu and impressive title spin offs really feel unfortunately like products of their time in the eyes of a lot of people.
i think a lot of the decline comes down to people getting tired of the culture of "rp with this pack/clan/whatever" for a day or two and then nobody...ever logs back in after that and the people who do never seem to catch up with the others- that was a thing that happened to me a lot back in the hundreds-of-people-online-a-day era when i was first playing the game.
the "everybody says they'll be there but in the end you know they won't" mentality only really changed when discord became a part of the scene in like.. 2017 i wanna say.
and there actually was an interesting balance there for a little bit iirc where there were groups that had discords but still logged in more often than not to actually rp- because of custom maps and the utilization of presets to make things more immersive and etc.
but a lot of it moved to discord and as you said a lot of it got toxic to the point of being unbearable.
idk what about these games with -no ranking system -no item value system -no competitive edge of anything brought in people who are ridiculously power hungry and will do anything to keep said power. i really don't get it. the goal of the game is to sit. and talk. it's mind boggling to me how people still think it's the perfect hub to act just a tad deranged. i'm sorry you've had bad experiences with these types of people in the silly little 3D animal chatroom game, i'm right there with ya.
i definitely agree that forums are sort of this dying art to be both a community hub and one of the best ways to categorize resources for a game. truth be told i like forums more than i like wikis though i don't really know if that's an uncommon mentality to have these days or not.