That player was doing that on purpose, and, if they weren't, it'd be even worse. By level 20 you'd expect the basics to be known, and build a more optimal, or at least acceptable, way to play from there on. Let alone a lv70 player. They don't give a fuck? Don't expect the rest of us to comply. End of the story. No one is asking for anyone to be the absolute best at their job, but come on. Thanks to players like you, they think they get a pass, and then we all gotta come across them in more difficult content.
You are missing the point as stated, or you are incredibly naive. Or both.