I’m currently in grad school, and I see lots of parallels between the trainer/student and advisor/grad student relationships. I’ve seen promising young scientists leave the field because of their harsh mentors, and not necessarily because they can’t deal with mean personal attacks, but because they don’t want to. And if that’s the only view of the field they get, then I certainly don’t blame them.
In both cases, I’ve found I can withstand and learn from the screamer/harsh authority figure, but I don’t thrive under them. I just don’t think a ‘beat em down’ process is necessary or accomplishes much beyond destroying someone’s confidence. Identifying/correcting mistakes and maintaining high standards can be done without being harsh. It shows a lack of respect for the other person, and honestly, a lack of creativity if you think the only way to motivate people is to yell at them.
Besides, if you compare it to training animals, it’s well-established that positive reinforcement of good behavior is much more effective than harshly reprimanding bad behavior. Well… humans are animals too, aren’t we?