The 4chan scum spread their poison to the rest of the internet.You and I seem to remember those dark days back in 2016 very differently. This wasn't just an outbreak in one scummy corner of the internet which them spread everywhere else, the poison you describe cropped up everywhere; 4chan, Youtube, Facebook, this very forum.
I was editing, deleting and banning people on a weekly, if not daily basis because of just how vile they were getting. They can't all have been 4chan users.
The aforementioned troll I used to troop with who mocked those sick and dying children used to be a member of this forum, and the UK-based costuming group I'm involved with. He may have had a 4chan badge among all the others he wore, but he was a homegrown Ghosthead who became an extremist.