No psychiatrist would diagnose someone based on public performances, and non-psychiatrists using pop-psychology to do so is very unpleasant.

This is a wider cultural trend too. The prevalence of Dunning-Kruger pop-psychology YouTube videos (again made by people with zero medical degree) nowadays "teaching" people to recognize "Narcissism", "Psychopathy", "Mania", "Manipulation" etc. is absolutely vile. Just teach people assertiveness and leave it at that.