Because only lefty wackos care what pronouns others address them by.
Do you think if someone is addressed by a pronoun they don't prefer, they will melt?
Why is courtesy a problem? Someone asks to be addressed a certain way. Whether it makes sense to you or not, why is trying to address them they way they requested so controversially?
In my mind it’s not any different than someone preferring a nickname, their middle name, etc.