My guild fell in love with be.imba and wowheroes a while back. Look, they have gear scores! Trumpets played throughout the geeky core of the guild: "Finally! A way to grade and communicate to people their relative progress in the endgame!" For example: "Hey, you're not ready for X because you don't have Y score. Go hit some instances and heroics."
Unfortunately, some time cuddled up to these tools have exposed why they can't be used for this reason.