I don't think so. If I were an extremist, I would write on all possible channels to have the biggest possible audience.
Sticking to one platform would minimize my reach.
But it will help to monitor such movements even better for news coverage, and or legislative orderings.. whatever.. and also it will help to radicalize of somes even faster.<p>And it will attract anonymous and hopefully distract anonymous from other planned projects :)
Social media with metrics is a failed experiment. The metrics need to go away and "engagement" needs to be based on something more substantial than getting likes and upvotes. Otherwise, democratic institutions will continue to deteriorate.