To attack people they disagree with, and do it in a dishonest and cowardly manner.
Yes, the internet is like a HS popularity contest. It's ugly, it's deceitful, it's false, and you're a fool for valuing it at all.
Social media exists primarily to make people who are essentially worthless do-nothing pieces of shit feel good about being worthless do-nothing pieces of shit.
Lowest common denominator always wins. Look at the recent GOP "debate" if you doubt it.