For the min-max progression guilds, I'm sure this would still be the case. For the more casual raiders and guilds (the ones that don't care that you didn't go engi/jc for that extra .03% min max), they're able to fill a slot regardless of faction, and if the player plays well, it doesn't matter if they're doing the min-maxed 12,648 dps if they can do 11,000 that's still viable, follow the boss mechanics (ie avoiding fire), and still pull their weight. It would allow those on alliance to be able to join pugs and fill the slot...some dps is better than no dps as long as they don't cause wipes by triggering mechanics that heal the boss or spawn unnecessary adds that ends up wiping the raid.