I agree, however I noticed this even back in late 2016 and pretty much most of 2017.
The bitter truth is that the Halo fanbase is slowly dying and people only come here when:
- A new Halo game is released.
- Misinformed that this isn't the real 343 website.
Besides from that it's just been the same 'regulars' who stuck around for all of these years, just to name a few.. Halofollower, Drizzy, RSR, Fishy, Yoshi, etc.
Basically it is what it is, the fact the forum is pretty much like the badlands from Borderlands at this point is because of the lack of interest in Halo anymore, plain and simple.