reddit is run by thin-skinned millennials who've had their self-esteem worshiped their entire lives and have never been punished nor reprimanded for anything.
Now they're finding out that Reality doesn't give AF about their precious feelings and they can't handle it. So they stomp their feet and do shit like this to make themselves feel like they have control over something.

Note: No, this isn't all millennials - just the leftist ones you typically run into over there.

TL;DR - they're all a bunch of fucking losers.