I've observed and even trained in a couple of hard styles when I was younger and had much more energy and physicality. Typically there are mostly male students between the ages of 16 and 35 but few females or those 40 and above. Also not atypical are the number of training injuries.
These athletic practitioners can become quite skillful but the people who are not so athletic and could benefit most from self-defense (the frail, the aged, and the majority of females) are not well-served by the roughness of the training methods.