Because you essentially gain 12 stats (4 int, 4 spirit, 4 stam) that benefit you greatly instead of the equivalent of 10 stam. Also, I've heard the best way to farm firebelcher "solo" is to group up w/ a friend and have your main and your twink be in the group, run in WC on your main, check for rare, if it's there clear up to it and solo on your twink. Rinse repeat.