The assumption that trolls are only motivated by a desire for attention and that, if ignored, they will simply go away like frustrated children in massively naive. Trolls are networked and sponsored by states now. They're weaponized. They'll find your address and harass your family. They'll complain about you to your employer. They'll send SWAT teams to your door. And they know that the internet is designed in such a way that as long as they keep spreading their nonsense they'll win by default. A lie can travel around the world twice before the truth laces up its boots, as whomever said.

That rule was fine when the internet was nothing but nerds LARPing on USENET and there were no stakes to anything but personal ego, but it isn't enough anymore. The internet is real life now.