I had a hard moment on the gamedev stackexchange where I was stuck trying to learn how to do something in OpenGL. A moderator immediately closed my question as a duplicate because there was a similar question about OpenGL ES, which is a (related but) different API. I tried to plead my case, but was shut down.
Shortly after that, I gave up on the game I'd been working on for a couple years. The mod's decision contributed to that.
I felt stuck by a wall between me and answers to some of my game programming questions. Over-moderation is more than an inconvenience. It can destroy the ability of users to get things done.