Exactly this. A GM that puts in a bunch of restrictions, or railroads the party, or includes a DMPC, isn’t necessarily acting in bad faith. I honestly believe that they think their ideas are awesome or groundbreaking. Or that if they give an inch their players will walk all over them.
Telling them “it’s their game” and that “when the rubber hits the road, it’s their decision” ultimately does a disservice to them.
The biggest thing that bugs me about all of this is the conflation of DMs that have a curated list of races or any restrictions with "a bunch of restrictions, or railroads the party, or includes a DMPC" that people do constantly. I'm playing Curse of Strahd right now and it is far, far more linear than any campaign I will ever run but because it's set in FR any race goes.
Which goes back to this thing that always seems to happen on these threads. On one side we have the extreme of DM as tyrant forcing the players to submit to his will. These games are always toxic because the DM is a cruel dictator.
Of course we have the people who think compromise can always be reached. Just add the new race or let a PC run whatever race they want but change the fluff. For most of this group, there is never a reason to say "no" except perhaps no flying PCs or no evil, although that varies as well. Compromise really means "Give the player what they want, the preferences of the DM don't matter".
Then we have people that have given reasons for why they have a few minor restrictions when they DM. They let people know ahead of time what those restrictions are. The setting restrictions are not done on a whim, they do it because they're just trying to run a campaign that works for them and that they will enjoy running.
I know where I stand, and what I've always seen. I've had good, bad and mediocre DMs, whether they limited some choices was no indication of what their game would be like. I've limited races for a very long time and my player retention rate is probably 90%, higher if I didn't count people that stopped because they moved (which sadly I've done too often). I have a curated list of races because I've put a lot of thought into my campaign world and that's part of what makes it work for me so that I can run the best game possible. I'd rather have a DM that's enthusiastic about the game they run than play a tiefling in a campaign where fiends don't exist.