I think changing the name doesn't take away the hate at the core here. People would be as fine with "fat-bullying" as they are with "fat-shaming", they see it as somewhere between "their social right" and "actually helping the person".

It is the same as changing "retard" to "mentally challenged" or "handicapped" to "disabled"... the next term just becomes equally toxic because you haven't changed the actual stigma, just the word used to express it.

The stigma is fine. It's the bullying that's a problem.

But recent efforts have been focused on blurring the lines here.

This is basically "heritage not hate" but for a socially-acceptable target. You're saying racist opinions are fine as long as you don't act racist.

The stigma causes the hate, they're effectively the same thing (I used them interchangeably) and leads directly to adverse actions against those individuals.

And the argument generally shifts at that point to "it's good for them to be attacked, maybe it'll motivate them". Because again, it's just a socially-acceptable vector for hate. We've gradually run out of other forms like racism and sexism, for a while it was homophobia (and the argument was that was a choice too, so it was fine to attack), but we'll always have fat people.