How many of these used Facebook, Twitter or Reddit? They are not mentioned in mainstream media because they are popular, but I assure you there are a lot of deranged people that never even posted on 4chan and just stuck to the “good” ones.

Or the countless people that like and use 4chan, and would never remotely consider perpetrating such a heinous act.

I see dog whistle (if its sufficiently subtle to qualify) racism every time I look at my FB feed, along with lots of ragebait and idiocy.

Yeah I don't think the 4chan demographic is substantially different from the "normie" social media. It's just that everyone speaks more openly about what they already believe there, including the crazies.