So Peterson characterizes the right as concerned with making sure that society functions efficiently and competently. And he characterizes the left as concerned

So Peterson characterizes the right as concerned with making sure that society functions efficiently and competently. And he characterizes the left as concerned with the inevitable fact that when a society is made to function efficiently and competently there are some people who get left out and fall to the bottom rung of society, and we need to make sure these people are taken care of and aren't completely neglected. So both left and right are unified separately by their own ideals. The right goes too far when it devolves into ethnic nationalism. When it says only people of race X are capable of being efficient and competent. The typical example here is Nazi Germany. The left goes too far when... well, that's the question. But we still have plenty of good examples when it happens. Look at communist russia, communist china, (insert more communist countries here). Most of those states outright failed to function at some level, and plenty of them ended up being genocidal. It looks to me that the left goes too far when it demonizes smart, efficient, competent people as thieves or other criminals, as the communists did. We are on the verge of that right now as the left denigrates people for being privileged, in such a way as if it were some kind of crime. Or perhaps implying that crimes took place in the past that were not brought to justice, and not suggesting anything in particular but the obvious conclusion is that those crimes need to be brought to justice against the people who are benefitting from them now.