"No celebrity in my lifetime before the advent of this new wave of cancel culture has been completely cancelled the way they are today"

But they have, this is the very nature of the infamous Hollywood blacklist: https://en.wikipedia.org/wiki/Hollywood_blacklist

Have you ever read "Time of the Toad" by Trumbo?

I think people would be blacklisted in exactly the same way in the 50s; this is all fairly well documented in relevant writings from the period.

I think we're in agreement that social media and specifically giving people access to publishing has changed the duration and discoverability of the speech.