As for providing some evidence of cancel culture and deplatforming, somebody would have to have been living on Mars (or have blinkers) to have missed the odious practices (as evidenced in the OP!) that the terms were invented for, and I'm not sure me spending my time googling and linking examples is going to help in that case.
But that only gets you part of the way to understanding. These arguments are & always will be abused. But: just because something is regularly abused doesn't mean there's no validity to it. And of course, pointing out that these arguments are abused is itself a kind of Quake laser cannon argument.
Ultimately, you just have to decide yourself based on context cues whether an argument is valid.
† Obviously, I am one myself
Now on pointing it out, I think a lot of people don't realize they are trying to sway the discourse thru the use of projection rather than logic and reason. I think it is one of those insidious things that just creep in and people don't realize they are doing it. I like to give people the benefit of the doubt and think they want to appeal to reason (at lest in life and on HN) and I think many don't see these words work in direct contrast to that, they literally appeal to the mob. I point it out not to gain net fame or quake guns (I will take a pack-o-punch'ed gun in BO Zombies though) but rather I would hope at least one reader of this thread would have the "I never really though about it that way" moments.