The problem with cancel culture is that it is, in its current instantiation and throughout history, almost never applied judiciously to bad actors who won't engage in good faith.

Instead, it's overwhelmingly used as an alternative to hashing out differences through conversation, and as punishment against people who haven't done anything illegal but who we can impact through social means.

You bring up Donald Trump, but he knows no shame, and canceling him doesn't work at all. It's completely pointless to use cancel culture on him at least from the left. You can't cancel someone outside of your tribe--you can only cancel someone within your tribe. Indeed, cancel culture can never really be stronger than excommunication from your tribe (whatever the relevant tribe is). This makes it suitable for controlling bad actors within your own tribe, but terrible for enabling us to "hash out our differences through conversation" because most of the people we feel like canceling already agree with us on most things...or we can't cancel them.

Yiannopoulos is a perfect example. His appeal was that he was trying to be canceled. The cancel culture was a total backfire. The people who wanted to cancel him weren't his tribe and thus had no power to do so. What he said wasn't that interesting, or that nice. What was interesting was the amazingly intense opposition he engendered--the willingness to break all the rules as long as you could keep Yiannopolous out.

If everyone said: "sure, come visit, but the week after we're inviting a speaker to debunk all your points" (and they got someone competent), then the whole thing would have been a huge yawn.

It wasn't the censure that made him go away. The censure is what got him all the attention! He went away because he got boring. And he had bad ideas--which got a far wider hearing than they ever would if he hadn't been attempted-to-be-canceled, but they just weren't compelling enough to sustain interest. (Edit: see also Alex’s comment for an alternative explanation for Yiannopolous’ fall from prominence — I haven’t looked in enough detail to be certain, so it is an especially good idea to consider his commentsand look into the details.)