Some people are bullies and use shouting at the band as a way of covering up their own insecurities or just psyching themselves up.
It's immature, unpleasant and in most cases unnecessary.
If the guy deserves that kind of treatment then replace him. If it's just a band leader venting recognise it for what it is, meaningless noise. Or you can fight back, but make sure you have another gig lined up. Just in case.