I would go so far as to say going to meetings physically was also a counterbalance.
When you're around other people, even ones who share your beliefs, and say 'I think we should murder that guy!' then in most crowds someone is going to say 'Hey fellow, are you okay?'
It's when you exclusively socially exist in online spaces that the most extreme actions suddenly become encouraged.
Or as Josh Johnson recently quipped, "The internet is all gas no brakes."
We might be thinking of different types of gatherings/meetings. Specifically, I was thinking of someone with a particular set of extremist ideals that get together for a monthly meeting with others with those same extremist ideals. Someone in that group would likely not say "are you okay" rather they'd say "hellzya brother!" or whatever they'd actually phrase it. These types of meetings are also known to have someone speak intentionally seeking to get a member to act as a lone wolf to actually carry out the comment you're hoping someone would tamper. Now, one doesn't need to go to meetings for that encouragement. They just open up whatever app/forum.
Where are these people going that they just see encouragement without resistance?
There are crowds where that guy is not there, is not heard, or doesn't speak up at all.
In those crowds, people reach out for their pitchforks and outright murder people.
If you take a frank look at history, you will notice those are all too frequent. Even in this century.
I'm telling this story because I think it's how things usually go, and I think you are quite mistaken.
If you walk slow the earth looks like a plane
If you go faster the earth looks like a sphere
If you travel really fast the earth looks like a dot. A tiny blue one.