That is all fine for children, but in real life there are many situations where displaying anger is a perfect tool.

In a movie whose title escapes me, Jack Nicholson plays an anger management therapist who is hired to coach someone 24h per day. He explicitly includes exposing his trainee to situations where he should display anger.

This whole 100% stoicism movement is quite suspect to me. It is mostly a thing for administrator types who read the 48 laws of power and some manosphere sites. It is also Orwellian, since complete suppression of emotions is a central theme in Orwell's books.

I've come to view it as a parlor trick for administrators to appear superhuman and unapproachable.

Actually creative and productive people are more in touch with their emotions and sometimes let them out.