Or you don't want to be harassed by someone taking your conversations out of context then doxxing you and trying to ruin your life.
http://wilwheaton.net/2018/08/the-world-is-a-terrible-place-...
He also used his real name. In fact, he didn't really take any steps to protect himself besides moving to mastadon. Large instances, after all, simply function like an unmonetized twitter.
I kind of think that's the point for a celebrity on Twitter or a similar site.