I saw the comment you're talking about, but I'm not sure I understand what it meant. What does a screen reader do other than skipping an image without alt text?

Either way, that person was also explicitly saying that they don't want mandatory alt-text, that they believe an option users can toggle on their own account to be reminded about alt-text is better, so I don't think they would qualify as "complaining about missing alt-text".

It seems they don't want it to be mandatory because people will likely fill it with nonsense, as your already suggesting, which is worse for them than it not being there.

I don't know what the screen reader does, presumably tells them there is an image there. I assume they want the option to remove the post all together.