I've had to deal with this myself on a few occasions when I DMed. One of the DMs had a bad habit of railroading and trying to play out cut scenes with us as passive observers. When I confronted him on this, he said it was his story. I told him to write a damn book if he wants his own story and that in an RPG the DM is the narrator and creates the narrative, but the players are the characters. It's a story that belongs to the group, not just him. Vastly improved since then. He gave his own critiques to my style (more combat heavy) and I grew from that as well.
I tried that with one of my first DMs and he just got offended anytime I gave him criticism, it became a derangement over time. He did improve on the railroad department but just barely: thinking outside the box for his encounters or puzzles was met with him pulling you aside "it doesn't work, sorry I don't want the encounter I worked so hard for destroyed" and that made me feel like shit, he squashed any creativity, and it wasnt like I was trying to godmode wizard or anything: my character was more of an investigator, he had several spells to help with mind reading and sending messages so he was meant to be good at that sort of thing.
Then the "D&D is bad!!!!" Bug bit him but for all the wrong reasons, the little retard whined about the system being bad at having balanced encounters (seriously, once he threw a death knight at a level 7 party) while never bothering to read the section of the DMG on encounter building and ignoring all of my advice and resources. They moved onto a system which used wounds instead of HP and months later he was trying his hardest to hack in hit points into said system, anytime me or someone else suggested to use a system that better suit their needs we got the
"I don't wanna learn another system"
"I like this system!"
So learning another system is too much work for you but coming up, testing and ironing out house rules that change a core mechanic of an existing system isn't? Piss off
Lastly his NPCs were obnoxious, he made so many of them and each had their own storyline we could hardly influence, unless said npc was your "designated" waifu or friend. He decided very early on who would bond with each NPC and if overtime your character bonded with one that wasn't your designated one? Well tough shit, designated waifu/friend was more important and left you on a second spot any time.
Lastly the guy was petty like you would't believe, he tried to get back at me and irritate me after I gave him advice or did something on my own games that upsetted him:
- We used roll20 and I decided to make all enemy spellcard and rolls private, he took a big issue with this and next time we played his game he did the same thing but was overly antagonistic about it, specially towards me.
- He would start complaining anytime enemies focused on his character and accused me of hating him (he also did this to other DMs to a lesser degree)
Overall he was annoying as both a player and a DM, and sadly he kept getting players since he was the only one to DM so often, a campaign would end and he would start another almost immediately, leaving others with no time to organize their own stuff and get players from that group. He was also a HUGE suckup, always trying to play in campaigns his friends played on, even if he disliked the theme or the DM.
Bonus: He would get really into a piece of media (movie, videogame, anime, series) and make characters who were very obvious references to said media to the point of being super obnoxious or on extreme cases add the character as is. Don't get me wrong I love being cheeky and adding a small joke or reference here and there like Jose Jostar but what he did made more than one person groan.