Do you think I don't run a game? Because I do. Admittedly, it's Dungeon World and not D&D, but close enough. (Indeed, I feel like I barely talk about anything else around here. I'm almost certain we've both posted in threads where I've mentioned how I run devils in my game.)
Doing so has made me even more convinced that it is vital beyond words for DMs to actively and passionately cultivate genuine, sincere player enthusiasm at every stage of play, and that by far the best way to do that is to be as supportive as possible for their ideas, particularly when it comes to baseline "what am I allowed to be?" and "what am I allowed to attempt?" stuff. I still expect my players to sell me on it (that's part of the process of supporting genuine and sincere enthusiasm, not abusive, coercive, or exploitative behavior), but my players know for absolute, 100% fact that if they have a reasonable request, I will find a way to make it work, though it may take on new forms or new interpretations before things are settled and ready.
(And, though it should go without saying, just because they can attempt a thing does not mean they will succeed--but I will never, absolutely genuinely never, tell them that they can try something and then play games to ensure that their success chance is effectively zero. If they can attempt it, it has a fair chance of success. If it's an "effectively zero" chance, I'll tell them that--but "effectively zero" means maybe it can be improved to be "unlikely but achievable," if they can succeed at other things first. The difference between mostly dead and all dead and such.)
Also, I love how "I just really like X, can we talk about ways to make that happen?" is now "[my] need to be the one setting rules."
Do you not see how hilarious that turn is? How you have vilified even the questioning, even the attempt at discussion (to say nothing of compromise)? You have literally painted me as some insane control freak simply because I want to sit down and talk with the DM about some limits to see if there's something we can work out. I would genuinely think you were having a laugh if I didn't know better, and it makes me sad that you are completely serious.
Because I have never--not once--"signed up for" playing only one specific thing. Literally every time I have ever played a game, it has been, "Hey, you wanna do some D&D? We can talk about character stuff" or someone posting a proposal online and, because they aren't foolish, not massively limiting what things people are allowed to play.
Because it turns out having adult conversations with people is actually really important if you want people to play in your games. As opposed to declaring that your word is law and those who question that are dangerous, subversive elements that must be exiled posthaste.