You don't even have to go that far back. Just 20 years ago the idea that being gay was ok would get you treated like an anti-vaxer today.
Go back 50 years and "race mixing" was taboo.
There was no broad scientific consensus about how being gay is bad 20 years ago. Banning from one particular private platform is fine, if people want to be anti-vaccination don't do it there, maybe it'll actually encourage them to stop wasting time on Facebook and contributing to the actual science.
Imagine a person like yourself, mainstream opinions, politically correct.
We now know he would be wrong on a number of things.
I mostly agree with you on a case-by-case basis it seems, but a little humility might be good.