Spreading ideas on the internet is spreading ideas to other meat sponges. I wouldn't consider most of the mass shooters of the past decade to be anything more than sad edge lords, but they've ended a ton of lives and ruined far more. Most skinheads are in loosely organized groups, not American History X or Sons of Anarchy with massive financial backing and tight-knit organization.

People have ideas, ideas don't have people.

If it was true that merely being exposed to an idea had the ability to take over and control a person like a mindless puppet, then democracy would simply not work, instead the only viable option would be strict control over thoughts and communication prevent harmful ideas from taking over peoples minds.

read about "radio milles collines" for something relatively recent

Rabble rousing is a different thing.

There's numerous examples of people being stirred into violent mobs over such things as the wrong person being considered for papacy.

e.g.

http://www.csun.edu/~hcfll004/SV1378.html

http://www.csun.edu/~hcfll004/SV1484.html

The ones who actually commit atrocities always start out as edgelords.

I'm not sure how I would even begin to verify that, but even taking it as true, it's necessary but not sufficient, but so is being a human being.

Edgelords always start out as babies, so … babies commit atrocities. Where does that get us?