This study makes total sense to me. I had some psychotic phys ed teachers growing up, ones that would make fun of kids for not doing a pull-up, ones that would yell at the kids for getting tired... the same thing happened in little league sports. I had coaches who would browbeat kids for screwing up, make the bad players never get any playing time, etc.. lucky I wasn't often the subject of those tirades.
Consequently this has shaped my life and how I deal with training people and when I was a coach as well. I always made sure every kid played (junior high sports) and that I wasn't negative towards them if they screwed up. I don't call people out for their lack of results, just a lack of effort. If you try hard enough and do your best, that is all anyone can ask..
its a shame that some teachers/coaches don't realize that.