One of the biggest reasons why people get worked up over "opinions" is that the phrasing seems to be all "wrong".
Like, asking a simple question like "Who's the best Robin?" and then someone, or other people interpret the question as "Who's your favorite Robin?". The answers that come out will definitely throw off anyone not accustomed to the language of such topics, which I think it can be pretty silly at times, but needs addressing.
Similarly to the rule of "No Fancasting" or "No fanfic" on this forum, the sharing of opinions would preferably need to follow that same logic too. People should be cognizant of what they're saying, and how they answer questions on here.
Like, what do you mean when you say "Henry Cavill shouldn't have cast as Superman" [paraphrasing]. Your comment isn't indicative of an opinion, it comes off as a fact, or it comes off as you having some authority to what should and shouldn't be.
I think it would've been better if you had said something along the lines of "I don't like Henry Cavill as Superman", or "if I was in charge, I wouldn't have cast Henry Cavill as Superman from the beginning". This makes your comment more evidently an opinion, YOUR opinion.
At least, this is what I've picked up from the "internet", which I think is just a terrible excuse to justify poor communication.