It has nothing to do with voicing opinion. It's the manner in which it's being done. They are making short, snide commentary, trying to be clever. They add nothing to the conversation, and indeed, are not trying to have one. They are merely trying to "make a point" or cause a stir. They have an agenda, and a civil discussion is not what they are looking for. They know exactly what they are doing.

On top of that, if they go bad and edit their posts, complaining about down votes, which should then earn them down votes regardless.

There are civil ways to hold a discussion. Many of these comments are not an example of that.