Oooor, not imagine the world as under so much constant attack that agrarian societies can't form independent of naughty words what give themselves crowns for stabbing people.
I'm not claiming D&D assumes a death world.
I'm saying D&D assumes a Medieval feudalism base then plucks halflings out of it and replaces that trope with nothing.
And someone mentions that the hole the game dug is empty, the response is "you fix it".
Except they do work for most people with just the base assumptions. If they don't work for you, that's a personal problem. No game can be everything for everyone. There's plenty of lore from previous editions and campaigns that you can import.
Or just don't use them.
They work in the base assumption because the players fill the holeorwait X years for a race book to fill it.
My problem is why D&D dug this extra hole it the first place and didn't fill it when they first adapted the race to a new assumption.
It's like putting TMNT in D&D sewers then specifically stating the lack of delivery pizza and of rodent ninjutsu masters.