The reason nobody REALLY wants Hybrids in a group is it takes a LOT more kills to reach say 2 bars on your XP graph than if the hybrid is not in the group. Then if you are the low end of the level in your group and the Hybrid is at the top level you are further screwed because the mob maybe Light Blue or even green to him. And if more Hybrids come in it is even worse.
I have been in groups in KC with a lot of Hybrids where I got maybe 5% gain in 4 hours playing. It sucked experience wise but was fun.
Sort of applies to the old joke in EQ if 6 Troll SK's grouped together they would loose XP.
[You must be logged in to view images. Log in or Register.] Probably not far from the truth if you we the lowest one in it.