Depends on what you interpret as rude. Plenty of people interpret blunt as rude, after I stopped masking (I was super polite and stoic as a child. Blunt, lively, and silly now and most people think I’m about 7-10 years younger as an adult) I learned to pad out my bluntness with things like “can I say something and sound like a bitch?” If someone is commenting on something that another can’t change then yes that’s rude and they should’ve been taught otherwise, but sometimes that doesn’t happen.