It’s not “fairly simple if you have common sense”. The known abbreviations have been in use for a hundred or more years and are widely known. Everyone knows how to pronounce them, the only curveball is Mrs being misses since it was originallymistress but that word later became associated with cheating and “ladies of the night”.
Mx was made up recently, it stands for nothing AFAIK. They just took the standard M beginning and slapped X on it because X tends to mean “unknown”.
It’s akin to asking you to address me as “Zf. Cat” because that’s what makes me feel comfortable.
They weren’t introduced in anything like an analogous way. Mr and Mrs evolved slowly over decades and even centuries from older forms referring to master and mistress.
I don’t have a strong opinion about Mx either way, but as an amateur linguistics nerd I can assure you that the way it’s been introduced to our lexicon is very different from these much older terms.
Ok, Zf. Cat :) If that makes you feel comfortable it costs me nothing to be considerate of your preference. See?
Now you have to remember that for every interaction with me. If you happen to call me sometime else, I’ll grit my teeth and have to correct you or if I’m an asshole, I’ll berate you about it, constantly. You will also have to refer to me as Zf. Cat to everyone you know, regardless of whether or not they know me, or are in my presence.
You should be asking yourself why you assume the person would react angrily instead of just politely correcting the pronunciation. If someone accidentally mispronounces my name I gently correct them, while smiling, and I have never once been offended or take it personally. You also assume it is a heavy burden on others to simply call people what they’d like to be called. When it is not. Being angry over this is not a healthy attitude. It’s simple manners to be considerate of others and that is precisely what the person is asking for, nothing more.
Except it’s not like that at all, because you just made that honorific up!
Mx. has an actual cultural context outside of their classroom. Sure, it’s new, but it’s not like this teacher just made it up themselves.