It's too late to stop the violence that's already happened. That's cheap and I don't like it but it's true sadly. There are real questions to be asked why the FBI weren't all over this from day 1. They need to be asked because it's (literally) their job to prevent this.
Im just suggesting really that we make the system work as it's meant to: FBI investigates, people plotting violence are intercepted before they commit it. Even if they are right wing nuts.
Im also pretty convinced parler isn't "responsible" in the sense that if it didn't exist there wouldn't have been violence (that doesn't excuse them for profiting off it). It would have been coordinate on r/TheDonald or via Facebook or twitter or wherever. Parler wasn't even a thing for most of the last 4 years and this has been brewing at least that long in my opinion. That's actually why I would like the idea of prevention. Banning parler gives us all an excuse to go back to sleep till next time and then (again) say "how did this happen?".
Thanks for listing to my rant!