We aren’t about to throw the whole Mussar section in the garbage, are we. We are born to work on ourselves. We all do get angry at times. I would like to think that I did work on my own anger.
It is indeed a challenge, since the opportunity to work on it usually comes up while you are mad. But it’s possible. And if there is such a thing as anger management I imagine it addresses that.
I mentioned here once before, IIRC, how working on Middos can take the form of self critique after the fact, until eventually you gain control.