Are there no reasons for believing that such confused, maladjusted young men have always been there, isolated in the shadows? Social media has allowed them to coalesce into an identifiable mutual support group that's lasted all of 5 months so far. They're now in the spotlight but without that it's hard to believe they'd have kept it up for much longer, whingeing about how unfair their mums, sorry moms, are to them.
I don't want to play them down- their views are disgusting and they're mostly American and there's more history there than here of serious tragedies resulting from unhappy young men with social issues. The Toronto driver may have been part of their group, his photo has been adopted by one of them as an avatar. Potentially they're dangerous, no question. But the whole point of their strop is that they're involutarily celibate, something that could change for each of them tomorrow if they meet ms/mr right. In that sense it's surely self-limiting?