I think if that was the case, the Dominion War wouldn't have ended with the Battle of Cardassia. I have to disagree with all that. Closing the wormwhole would have been an excellent strategy. If the wormhole had been closed at the first sign of trouble, it really would have saved a lot of lives from being lost and it also would have given the Federation an incentive to stay out of the Dominion's way should they have ultimately reached the Gamma Quadrant on their own many decades later. In such a situation, first contact with the Dominion would have been a case of perhaps only one Federation ship exploring the Gamma Quadrant rather than a massive colonization movement (which they perceived as an invasion force) suddenly on their doorstep. It seemed as if the Dominion's primary motive for launching an offensive upon the Federation was based on a fear that the Federation had come to the Gamma Quadrant to invade their territory and conquer them. Indeed, the first Jem'Hadar commander we saw gave our heroes a warning to stay out of the Gamma Quadrant, an idea that was dismissed by our heroes out of hand and one that the Dominion knew would be. It was really a case of the Founders lashing out after being persecuted by solids for untold ages. They established the Dominion to create a nation where they would no longer have anything to fear from solids. The Karemma, actually flourished under Dominion rule while more resistant races didn't. The Dosi weren't actually members of the Dominion, but had some sort of trade relationship with it, suggesting that not every race the Dominion encountered was conquered.