Skitty, I don't want to sound rude, but it sounds like you just don't get it. I've seen Uxie donk in action only a couple of times, mostly because nobody in my area plays it. In both cases though, the other player went through their entire deck in a single turn. This is because of Uxie's Setup power, allowing you to draw up to 7 cards when it's dropped. Add in Super Scoop Up, Seeker, Pokedrawer+, etc. and it's easy to go through most of the deck. It's during this process that Crobat G's and Poketurns are dropped.
With Sableye, donk decks suddenly get the chance of going first even if the other player should have gone first. Then, trainer explosion! If the other player starts with a lone Spiritomb, Pokemon Collector for a Crobat G and Unown Dark to win. If they bench another Pokemon, there's always the chance to use a Cyclone Energy (though I will admit that this would be hard to do). In lots of cases, however, the Spiritomb start might not happen.
With Uxie donk and new B&W rules, you practically win every time you go first. With Sableye added into the mix, you have a better than 50% chance of going first. And even though it might not be the best deck to play, it certainly is the easiest. Plus, with the entire format revolving completely around speed, I don't think anyone's going to pass up the opportunity to play the fastest deck known to this game.
Now, for anyone still questioning the legitimacy of Uxie/Sableye Donk in an MD-on format with the B&W rules, go do some playtesting like StormFront did.