I'm more concerned about even regular 'ol AD&D. By fifth level I (my wizard that is) was pretty much using my party for meat shields while I killed monsters.
...throw the entire game out of whack. Some wizard spells do that, and excessively focus abuse of rules do that....
If you were using other player characters as meat shields on a regular basis, there may have been pacing problems... That sort of thing might happen once in a while, but it should also happen that a wizard is pretty much out of spells and has to rely on the meat shields to keep him alive, while he cowers. I'm sorry -- I meant 'fighters' there. Spells can pack quite a punch, but swords don't vanish from your hand after you swing them. (Okay, sometimes they do. But maybe that's just me.)
Within a session of play, one character may trounce all others. But if it happens that one character is consistently in another league when compared to his fellows, there are probably DM issues, particularly not creating enough variety in the situations the characters find themselves in, or allowing too much rest time and therefore spell-recovery time. Mis-reading of spells can also make things lopsided. We recently had an issue where blade barrier
, with it's radius of 5 feet per two levels was thought to be an area effect filled with blades
-- not an area surrounded
by blades that careful re-reading revealed...
Meanwhile, we do agree that fear is good.