Depends on the culture(s) of the professional and their audiences. The more mainstream one wishes to be, the more one need mind the simple manners one's mother (should have) learned one. The more niche, the less consideration for your "others." eg: Clueless or inside jokes. Punching up, down, sideways, backwards-over-the-shoulder-with-a-mirror... is always punching.

Professional Trinidadian calypsonians will insult the last and next act in one lyric. American rappers 'disrespect' each other live on the same stage and alone in the studio... and they really do mean it. It's roots are very African but even the Euro-American chantying video game assassins these days are relearning their own lost art of flyting.