Those people are competent to judge whether their particular clients are, in fact, engaging in an activity that is toxic to them, whether because of the nature of the activity or because of the nature of the person.
As a general rule, however, the position on the ground obscures any view whatsoever of larger trends.
I've been involved with both. Clinical work, regardless of flavor, is a bad place to get a perspective on the average person. You are literally surrounded by the people who were having enough trouble to seek help or be forced into seeking help. As a general rule, people don't choose to spend time with a therapist until their life is getting pretty broken, and they are outside their coping skills. This is only the people who are in extreme need of help, as a general rule, outside of some urbanized areas where the stigma has been sufficiently eroded that seeking therapy is just another form of hypochondria at this point. It's damn near a merit badge in certain societies nowadays, but again, those are NOT typical people either.
So.... making broad statements about the human condition based almost exclusively on those who aren't coping well with the human condition is perhaps even worse than your average academic psychologist, who bases 90% of his work exclusively on upwardly mobile college attendees between 17 and 23.
Like I said.... I got the heck out of that line. Doing 90% of your work in a way that isn't remotely generalizable to the general population is a bad way to make progress. Or sense.