I try my best not to offend anyone at work, but policing my language to match the preferences of everyone around me would be exhausting. I grew up speaking a non-prestige dialect. I have a lifetime of experience policing my words. It can be exhausting. It’s easy to underestimate the mental cost if you speak a prestige dialect.
I spent a few decades being made fun of for saying y’all. I now find it a bit weird people who would have made fun of me for using it 20 years ago now use it themselves. I’m not offended by it, but my preference would be that non-southerners don’t use it.
However, I realize that it would be a bit much to ask that of everyone I interact with. And if I did it would be insane to label people who didn’t comply assholes.
I prefer that people that people don’t use learnings instead of lessons. I prefer not to be referred to as a USian. But I don’t expect people to follow my preferences.
Not the person you're replying to, but my take on it: because in the grand scheme of things it's small potatoes, and putting even a minor burden onto someone else to change their language seems unreasonable and unnecessary.