I've been finding more and more that I have to bite my tongue around people, even that I know also. The most upsetting part is when you see otherwise intelligent people fall into fallacious anti-patterns. One such anti-pattern that I see right now is black and white reasoning. For instance disagreeing with something being labelled racist means you support racism. Essentially, if you can shift the conversation from a complex topic (is this action racist) to a simple one (we shouldn't be racists) then it becomes easier to form an opinion and castigate your opponent.
I have to wonder how much of this is the person on the other side trying to copout of a topic which they haven't thought about, versus the influence of twitter-like agitprop. I think it's likely a fusion of both.