Mainstream left-wing media and leaders have not had corresponding calls to violence, though there are violent extremist groups on the left too, and a bloody history from Communist revolutions, Weather Underground, Red Army Faction, etc.
What's missing from the leaders of both sides are strong commitments to non-violence, as there were in the Civil Rights struggle in the US and Indian struggle for independence back in the 20th Century. Only something like that has a hope of defusing the ever-growing political powder kegs in the US and around the world.
Have there been any Republicans that threatened legislators?
There have also been plenty who seem to have no ideological motive.
My point was that no single ideology has a monopoly on violence. Some like neo-Naziism or militant leftism might attract it more but the extent to which they do is limited by supply. Right now we have a whole lot of supply in the form of angry alienated underemployed people.
Which is to say, there are plenty of other plausible explanations to consider when a large group of people start behaving in what is an abnormal manner in contrast to the prevailing culture.
