Well theres a number of reasons for that. For starters, Im under the impression that a lot of people have left.
Its been running for so long, threads are repeating themselves.
The age of the users is a bit high - I reckon most active users to be between 20-35 if memory serves me, so theres no time to invest to something like an internet forum.
Like, honestly, I dont care what you people say or think, Pokemon Sword and Shield are crap.
I dont know if theres such a word as "overmoderation", but if theres is, in few sites have I found it more present than here. Its impossible to have a proper conversation criticizing or bashing something we legit dont like - cause its taken as an "unproductive conversation". I keep hearing all the "good" folk got permabanned long ago. At times, the thread itself might not be discussion-worthy, and still gets locked. Just a couple of days ago they erased the "unpopular opinions" thread for no reason whatsoever. There was no insults, discussions, or anything of the sort, just a bunch of dudes sharing a bunch of unpopular views, and yet they locked it. So unless im here to say "X" thing is awesome and I hope it does well", discussions are limited. Seriously tho, Pokemon Sword and Shield are crap.
Its not just the moderation tho, people in general get triggered very easily - and in general are very serious in this particular forum. I've said this before, but bar a few people I find the treatment people have with each other in here to be very stiff. Even in the offtopic threads.