the type of fantasy setting based on D&D, where the population density and location of settlements are based not off of any actual medieval research, or thought-through material analsysi, but rather off of vibes largely inspired by the american wild west. Those vibes are then integrated into many fantasy works without any interrogation of what they would mean for the setting

It really only works for post-post-apocalyptic settings imo. You can get a depopulated setting full of lost knowledge and eldritch horrors, a land scarred by calamity, fortified survivor enclaves only slowly reestablishing new population centers as the land becomes viable again, etc without all the weirdness of D&D style "wait, why is every town basically just an exurb that's surrounded by a monster-land theme park?" fantasy worlds.

As controversial as Mushoku Tensei is, it does deserve a lot of credit for trying to rework the cliched fantasy land framework into something coherent and semi-realistic: there are people absolutely everywhere, even when they're not human they're still fundamentally people, and the places that are sparsely populated are basically full of magical radiation that makes normal plant and animal life almost impossible as it causes rampant mutations that monsterize them which makes those places very dangerous. It also did the Dungeon Meshi thing of dungeons being a sort of magical being that grows over time, except it did it earlier and better despite this basically just being a footnote to the rest of the story.