IMO their statements are amplified by things like national media because of their extremism; the extremism generates strong feelings (whether positive or negative), and strong feelings leads to more eyes on the media for longer. That doesn't mean the people consuming the media also have those extremist beliefs.
I don't have Twitter.
> Literally none of them ever mention Twitter in daily conversation. (And many of them are software devs.)
Network effects do not cause or force you to acknowledge a source. They merely require you to trust the mental gymnastics of the person who communicated the idea to you.
> That doesn't mean the people consuming the media also have those extremist belief
Generally the people adopting will adopt bits an pieces, this is what I described as "decay".
The rest I agree with.
I'd argue the opposite that you are. Twitter extremists influence the rest of the nation and it's easy to see how the network effect has some decay on their ideas, but the thorny points remain.
At some point you have to stop treating Twitter and Twitter users like an isolation zone.