Is this actually true or is it just something people say? I feel like there's plenty of room for people to grow or change their beliefs these days, it seems like every other day someone in power or in the spotlight says something like "oh that was something I used to believe but I've changed since" and that's kind of the end of it. Rarely do I feel like someone is entirely blacklisted for some opinion they held in their past but no longer hold, unless that past behavior was either abusive or straight up mean. Maybe I'm just not tuned in enough though.
The only thing I worry about is that some belief or comment could be totally benign today, but who knows in 30 years it might be totally taboo. Surely things I've said 30 years ago would get me fired in today's environment of heightened sensitivity. I don't worry too much about that because in 30 years I'll be retired and un-cancelable, if I'm even still alive.
"What's become clear to you since we last met?"
But that doesn't qualify in my mind as "proof you won't get in trouble on the Internet". Especially, I certainly don't want someone else dictating that what I post goes on a specific which can be linked to other things later.
(if your response is that those people deserved it, then you are necessarily also admitting that, no, there isn't really room to "grow and change", if the thing you said offends the wrong people in the wrong way)
I feel that "anyone can comment everywhere"-model just doesn't work for these types of discussions without heavy moderation to restrict the assholes; maybe one policy is "less bad" than some other policy, but it's still bad.