I d say no, from looking at some 70s who got a 2200+ rating, but still he got some very impressing 7000 Achiev-Pts.! I wonder how he got "Direbrewfest-Kill Coren Direbrew." or killed the Event Frostlord in 2011...
With the random dungeon finder, have a buddy lock summon when someone drops group (or you vote kick them).
Old school style, you'd have to fly out there or use the remote, then you could bring who ever you wanted as long as they were high enough to zone into the instance (60 for coren and 70 for frostlord).