Needed Gear rating to start FPs? Oh! I have a great idea for an Add on.... somehow it should read out all the ratings of the gear, that person has and then give out the average amount.... I shall call it... hmmm... Gear Rating. so don't even think about showing up with a GR below 120, if you want to come along.
And we are right where we were with WoW and that even without a dungeon finder.
Regardless of how everyone feels/felt about GearScore, there is *some* validity to the idea that a certain level of gear is needed to do hardmode instances.