Without a campaign world there is no game.
Eh. There's a whole lot of assumption in that statement as to what constitutes a game world. I don't think diving into this would be constructive, beyond stating that I, and others, have and can run games in which the game world is, essentially, "there's a village out there where you can buy food, arrows, torches and stuff," but little or no other explicit detail. Facts of the game world will be revealed as play goes on, "We have an elf and dwarf in the party, so there are elves and dwarves in the world," and "Oh, hey, here are lizardfolk on a pirate ship - so that's a thing," Improvisational D&D is a thing you can do.
And, as I have noted above - that a game world exists does not specify
how it is generated. "The GM makes up everything" is by no means the only way to go about things.
The players have a huge impact on my world's reality through their actions and decisions. Things that happen in a campaign become part of the world's lore. You have no idea what my campaign is like but equating a handful of limitations with a dictatorial railroading DM is pretty insulting.
So, I have already noted that the answers to your question clearly don't apply to you. I am not talking about what you are doing. I am talking about what other people, who are decidedly not you, do, or may find useful, and why.
Please internalize that, or this will continue to be you finding conflict in things that aren't about you. This will not be constructive, and will quickly become tiresome.