Honestly, short of a thorough and robust statistical breakdown of every Neogaf discussion on Man of Steel, I don't know if I can give you evidence that you can agree with. I doubt a link to a specific comment does anything other than call a poster out for no good reason. Feel free to disagree with my anecdotal evidence though, I agree that it isn't really conclusive proof of anything.
It's just that I can guess the kind of replies I might get if I criticized Man of Steel, something I can't say if I did the same for Age of Ultron.
Of course, only one of those movies has been out since 2013, and isn't going to have a follow up until next year. If these sorts of discussions have happened before and people are sick of it, I can't really blame them.