You'll also note that mainstream conservatives refused to condemn the Colorado Springs shooting and there has been no change in the rhetoric that encouraged it.
> Even if effectively 0% of people hold extremist views (and I think that is a low number), they also commit outsized acts of violence.
Sure, that's true. But it's always been true and, AFAICT, will always be true. But they are such a tiny number of the total population that they aren't the gatekeepers to progress on big social issues.
There is a tendency today to give people like that the spotlight and to paint everyone the slightest bit on the other side as being of the same ilk. Both of these things are mistakes that give those extremists power they couldn't otherwise get.
Backing up, the context here is the notion of finding some middle or common ground instead of splitting into warring tribes. When we fall into the trap of believing that the other side is full of people that look like the extremists on the other side, it eliminates the possibility of there being a middle ground. The result is a deeper divide, utter despair, a lack of progress on resolving issues, and often more people moving to the extremes.
OTOH, when we recognize that the extremists are in fact extremists (i.e. statistical outliers), it's empowering and hopeful. The distance between your views and those of the vast majority of people on the other side is actually much shorter than the distance between your views and those of their extremists (and even likely shorter than the distance between their views and the views of their extremists). It really is a bell curve; don't buy into the lie that it's an inverted one. There is an abundance of potential allies (including the main ones that have a real shot of deradicalizing some of those extremists), most of those other guys are pretty decent people, and real progress is plausible.