It doesn't have to be. I think people are still adjusting to social media, and the idea that everyone and anyone's opinion can get attention. Then there is the fact that people's opinions are held on permanent record, so they double down on their often misinformed opinion.
For instance, the "Clock Boy" incident. When that came out, I immediately saw very strong opinions about how he was wronged, society's terrible, etc. It soon came to light that there was more to the story, but no one wants to be wrong! They have been mouthing off, calling "friends" names, connecting the story to a myriad of other societal ill's and injustices, and generally digging such a deep hole, that they will never want to admit they were wrong.
I see this with Trump haters. No matter what he does, they have dug in on "he's just like Hitler", so there is no room for compromise. They have staked their entire identity on opposing him, driven by hysteria mostly generated by the mainstream media.
I swear, I have NEVER seen someone come back on Facebook to correct some silly misinformation they had disseminated ("Oh, sorry, this was actually bull ****...my bad")..never.