In the unified rules of MMA damage is not it's own criteria - although I believe when the UFC does thier little pre-fight rules thing it makes it look like one.
It's actually a sub-component of effective striking, which takes into account quality of strikes, quantity of strikes, as well as visible damage, "rocking" (stuns) and knockdowns.
This is why the judges saw the fight the way they did - GSP landed more power shots (most important sub-criteria), however condit landed more shots and they were both visibly damaged. GSP maybe a little worse for wear near rounds 4 and 5, but thankfully the fights aren't scored on what fighters look like at the end of the fight. Judges score each round as they go. Condit looked a lot worse for the first half of the fight than GSP did. GSP would have won the "damage" category in rounds 1 and 2, probably not 3, and the others were a toss up. It was towards the end of the fight that Condit would have scored points for damage. Plus GSP dominated in every other category the entire fight.
It is included in effective grappling as well and is viewed separately from the other aspects regardless because it is heavily weighted. It isn't like the fight is scored with a checklist and if you win 3 of 5 or whatever you get the round. It is a matter of relevancy what happened for what amount of time to what degree and how are those things weighted within our criteria.
I don't know who is arguing that Condit won the fight because he didn't but that doesn't mean the judges got the scores right.