I don't disagree with this entirely, but the right is spreading a mind disease of bigoted nihilism and self worship, combined with aggressively pushing traditions everyone knows, so their internet outreach is fundamentally compatible with online culture to begin with.

It is much more difficult to pull people left because we have actually have expectations, are trying to build a movement, and are trying to teach people things that run completely counter to everything they've ever learned.

It literally is the difference between education and indoctrination.

Plus, they're mainly trying to do stochastic terrorism, which is the main thing internet radicalization actually accomplishes. I'm not completely against that if people start picking the right targets. But left wing radicalization is based on the idea that things don't have to be this way, which is a personal, rational appeal that's hard to pivot into a desire to martyr yourself for a better future, let alone join an organized movement that currently doesn't exist.