>it's become impossible to make a single simplistic map for an existing shooter that your friends actually play

Counter strike global offensive still has a level editor. Though yeah fewer games nowadays ship with the community servers and mod tools you need to have that kind of organic community. Guess its mostly a problem with the changing monetization strategies where you want to sell microtransaction cosmetics which probably couldn't compete if someone could get whatever goofy modded cosmetics people added to their servers.