There's unironically a bunch of Appalachian cosmic horror stuff out there. In fact iirc Savage Worlds has a setting for it called Holler and Monte Cook games published a ttrpg for the Old Gods of Appalachia podcast.
Also if its from the developers of the system you also, hopefully, can assume that they are keeping with their own visions and intentions which should be healthy for the system. Even if its just "Story" content, it'd be really weird to see a room full of random sci-fi crap in what has up until that point been mostly a gritty fantasy dungeon.
Also, people can rail against this all they want, but people tend towards authority. The developers and publishers saying X feat or edge or whatever is useable in X setting, it doesn't leave a lot of room for inter-group bickering about it, but even then its opt-in.
Yea this is 100% the issue here. If I wanted to make content, I would, if I purchase a book with content for a specific setting or scenario, then there had better be that content in it.
Idk. I kinda of expect that when I buy something that all the information I would need would be present. But, I guess if you like having some of the information only, then it makes sense there's no rules for sailing space ships in the space sailing book. Especially since they charge you the same for modules with half the information in them as modules that have all the information in them.
Really d&d 5e is a mid system from an increasingly mid company.
I have a friend that worked at a studio as desk side IT and he got randomly terminated by Sony. The right after they hired 4 additional managers for their 10 man team.
If your company is losing money it 10000000% should start at the top.
Honestly, breaking away from D&D has been amazing. We've learned so many cool new systems and honestly, it's been a lot of fun.
There's a lot of smaller systems out there that are amazing, don't just try pf2e!
I loved that novel.