According to metalsucks, it's because metal singers are big babies. Don't get mad and stop reading, I don't mean that literally. Well, wait ... I kinda do.
A professional coach has two very important jobs during the game — to motivate men and to get other people (mainly officials) to see his point of view. It’s incredibly difficult to do either of those things when you’re jumping around, screaming and carrying on like a little girl that just got tossed out of an ‘American Girl Doll’ store.