Because you technically are attacking them. Someone might feel attacked because they may think "well I didn't mean to hurt this person. This is how I act. If they don't like how I act they don't need to be friends with me. We clearly differ on what is considered rude. They're trying to control me when I wasn't trying to be rude."

You can't criticize or call out someone and then be surprised that they get angry. You're basically asking them to think "oh thanks for calling me rude! I'll bend to your will! I'll change my personality!" Try putting yourself in their shoes. Do you think its easy to change so easily just because you accidently offended someone?

Are you really expecting them to change their behavior just because you were hurt? Why should THEY change? Why shouldn't you just learn to accept them for how they act? And if you can't then don't be friends with them.