No worries, I share your frustration about not enough being done. My point isn't that we should give up, just saying that the current state of academic research is insufficient to help with early warning. Other measures need to be taken.
Of course radicalization is not a new phenomenon but the escalating effect of online communities is fairly recent... from a counter-terrorism perspective, all the procedures, laws and capabilities are shaped by decades of identifying small cells and key inspirational figures, it's not geared towards fighting individuals and crowd-sourced extremism (although the rise of IS did accelerate countermeasures in this area).
Some of the measures that would be required from a practical standpoint (like mass internet surveillance and device tracking) just aren't acceptable to free societies and would create their own problems (like not having enough manpower to process the amount of data.)
The calculus is something like: security services look at 20,000 members of a radical community, then filter that down to 200 at-risk individuals (based on the imperfect scientific profile of these people) and then selecting the 10 or 20 extremists that have enough priority to allocate precious manpower for investigation and observation (imagine teams of around 25 people working on each case)... only so you can maybe effect 1 or 2 interventions (e.g. arrest) by the time the legal case is complete. Those aren't great odds and there are guaranteed to be misses, as in people who flew under the radar or weren't high enough on the priority list.
I'm in favor of deplatforming and causing maximum friction for these people to find inspiration and community (the die-hards will find a way but if you make it harder, maybe the community shrinks from 20k members to 2k members which is much more manageable for security services as per the above calculus.)
The best way to do that, as far as I know, is to pressure platform holders, legislators and regulators through political action.
Looking at annual public reports of EU security services, the trend has been pointed out for years now... that certainly didn't have enough of an effect and I'd rather we do something before we suffer the same lunacy as the US is currently going through.
