There are two sides to this.

One side is the speaker, who is responsible for not saying something hurtful. This is obviously flexible depending on history with the listener, the listeners stated preferences, and the context of the speech. (For example, my youngest and I routinely greet each other extremely harshly, and to an outside listener it would sound like abusive language. But to us it’s just friendly banter.)

The other side is the… listener? I don’t know how to refer to this side tbh. Anyway, they have a responsibility to tell the other person when something hurtful has been said. Because the speaker has no real way to know hurt has been caused unless they are told.

So if the speaker calls the listener dude, and the listener never says “hey I don’t really like being called dude” that’s on the listener. But if the hearer does state that, and the listener continues to call them dude, that’s on the speaker.

That got weirdly complex in my brain at the end for some reason so I hope I made sense.