> What exactly is the difference, again?
Think about 2 situations. Person A, wants to see the content of Person B. So person A voluntarily chooses to see the content.
And the other situation is Person C, does not want to see the content of person B, so chooses not to do so.
> there is no manageable way to block all of them
Yes there is. Someone could choose to allow an automated method of blocking people that they don't want to see.
As long as nobody is forced to use this automated moderation, or can change it, while still having access to that platform, then it is fine.
> Now you have a separate centralized platform for dealing with a certain subset of users.
No actually, it is quite a bit different. The difference being that a person could chose to modify this blocking authority. It is all fine and well to have blocking authorities, as long as I, the user can turn it off, if I choose to do so, on that platform, or otherwise modify my own blocklist, or add a white list.
So that is the solution. Feel free to have blocklists. Just let me change the blocklist, for myself, if I disagree with it.
There, everyone gets what they want.