I realised this very late, but it is almost like asking people to give up on coffee. You could probably get them to replace it with something else but you cannot remove it from their lives.
It is all about filling the void.
"I know a man who is building an advertisement-free Facebook replacement because he agrees with everything I have said critically about Facebook. Except, of course, for one thing: he believes the world needs Facebook, he just doesn’t like the Facebook we have. It’s like how at some point in our past, we agreed that the world required fizzy, brown sugar water, so the alternative to Coca Cola wasn’t no Coca Cola (or the abundance of other things you could drink), it was Pepsi. Why is the alternative to Facebook your Facebook by another name?"
To me, it makes 100% sense. Alternative to X should be kind of X, except minor changes here and there. Otherwise it is not an alternative, otherwise it is completely different thing.
Facebook, but a bit less like Facebook sounds like smoking 20 instead of 25 cigarettes a day, doesn't it?
The guy apparently believes that what is wrong with Facebook is ads. So, he is building Facebook without ads. If he succeeds, there is no harm.