If they weren't provoked then that's pretty stupid of them! But I can kind of understand their frustration, because I've heard the same thing "fast playing is emotionless or souless." Which makes no sense. You can get just as much emotion out of any piece of music regardless of speed. The tempo definitely affects music, but there are so many different combinations.

But the original shredders chose to play fast because speed evokes aggression. It can make something sound more powerful or emotional. But I don't have to tell you that! I'm sure you're already aware. :)