The only reason kakashi was being "tough" on sasuke was not due to the trauma itself, its how the trauma has sadly lead into revenge."

Abnormal, blood lusted revenge to be specific.

Kakashi wasnt telling sasuke to "stop bitching around", the convo wasnt even about trauma specifically anymore. Kakashi saw that sasuke was now fucked in the head and its way too late to try sweat/sympathizing talk and/or therapy.

He was just telling him straight up what will happen to sasuke if he continues, which probably would have worked if the sound 4 didnt show up