When a person writes something and posts it publicly (a blog, a news item, whatever), if there is a way to give feedback to the writer, then inevitably someone will disagree. Aside from "water is wet", there will always be someone who disagrees.
That's not a problem. What is a problem are people who allow comments but then don't want to hear them. They made it possible for people to disagree, then got upset because someone did disagree.
Such people don't want disagreement or feedback, they want sycophants. They cannot abide the idea that anyone can or could disagree with their opinion, taking the arrogant attitude that only that writer knows and has all the answers. Anyone dares to disagree is insulted (who cares?) or the writer takes the coward's way out and blocks the commenter. If a writer is going to do that anyway, not allow any disagreement, why allow comments in the first place?
I'm not defending trolls or people who go out of their way to be obnoxious, not at all. People who incite arguments, who spam, who post hateful slurs of any kind, they need and deserve to be blocked, exposed and in some cases reported to the police.
But if a person doesn't want to hear disagreement, then one shouldn't post in places where disagreement is allowed. A person who can't tolerate the thought that someone else might be right shouldn't say it where someone who knows more might read it.