It's not simply politeness. It's ideological speech which many progressives want to make legally compelled speech.
For eons gender has been a synonym for sex. Progs are attempting to separate the two and redefine gender as stereotypical masculine and feminine behavior (with the end goal for many progs being to discredit the concept of biological sexual determinism entirely). By playing along with their manipulative pronoun ritual, you're giving it credibility.
I'm not playing along with your goofy sex cult.