I think its because of a gap between spoiler and chapter release..ulike OP we get raw and full translation text early
When chapter released people already have discussion in spoiler thread and there is no much more to discuss
The arc's beginning was pretty boring and it's only now that it looks like it's slowly will pick up its pace. We either have work or whatever to do irl. Most people reading this here are adults. It is really easy to forget about it. To my knowledge the scanlation team for Kingdom changed and either the quality or release schedule went into shit.
+ Spoilers/raw come out way earlier and by the time chapter is translated the content of the chapter is pretty much "raped" by everyone.
The anime fumbling so hard made the series a nonstarter for millions.
Far fewer people get started on a popular series by reading the manga, which is what anime adaptations are primarily used as advertisement for, because there really isn't much money in animation outside of box office success, and the real money is made in manga, merchandising and licensing.
Kingdom has an uphill battle with respect to gaining new readers. The latest anime seasons seem to have stepped up their visuals, but I think they should've gone back and redone the first season in an entirely different style and carried on from there. I actually don't know what the fuck is wrong with some of these media conglomerates in Japan. They did the same thing with Tokyo Ghoul - a highly successful, critically acclaimed manga series praised and known for its gorgeous art, and they put out an abysmal, downright ugly anime adaptation that spun off into its own, mediocre narrative. Who the hell knows how much money they could be making right now if they had shepherded that franchise with the care and attention it deserved?
Kingdom isn't quite in the same boat with regards to its plot, it is after all loosely following history, but I still come back to that ugly, deeply unimpressive and off-putting animation style they went with for with the anime. Just imagine if Kingdom had been given the same animation style and resources as a Demon Slayer or Jujutsu Kaisen? Kingdom should have a much bigger presence in the Western anime and manga world than it does. The appeal is absolutely there.
The forum (and much of the fanbase, really) is split into factions which make it difficult to have chapter discussions. You have those who read the spoilers and exhaust their opinions amd you have those who dont read the spoilers. Add to that, an inconsistent translation release and the fact that we have the quick translated chaps, then the sensescans translated chaps etc.