The issue is that through 'retirement', fighters get removed from the testing pool. In that instance, the fighter, USADA and the promoter know that the fighter is out of the testing pool, but the public and his next opponent do not. It creates a possibility for selective standards with millions of dollars on the line. Brock pissed hot pre-fight. Vitor pissed hot prefight. In both of these instances, the fight wasn't cancelled and in one of the instances, it is verified that the UFC knew and didn't cancel the fight.
Fighters can retire and unretire at a whim without the public or their opponent knowing about it. The UFC doesnt release an updated roster and USADA doesnt release the list of fighters in the testing pool and any status changes (like retirement).
So as of now, a fighter can 'retire' secretly. Then go on a year long PED binge. Then unretire, rejoin the testing pool and fight 6 months later, or just get a waiver from the UFC and fight in a month. Under this scenario, neither the public, the athletic commissions nor the fighters opponent would have any idea that the fighter just came off a year of being certain that they wouldnt be tested.
Tl;dr even if its never been used, there is a systemic loophole that would let the promoters and antidoping agencies selectively choose which fighters are and arent allowed to use PEDs without breaking any rules and without informing the public, the commissions or the fighters opponent.
With the amount of money potentially on the line, transparency is important. Both UFC and USADA are claiming to be very transparent about drug testing procedures, but neither will release the list of fighters who know they wont be tested.
