Testosterone is a big role in dominance. Women who undergo hormone treatment, for example, find themselves more assertive, dominant, and possessive then before. Then there's the social issue that men are raised to be tough, and to control their women. Men need to be tough or they're perceived as weak.
I've got a fairly dominant husband, he definitely controls the relationship, but that doesn't mean that I'm powerless. A woman can be with a strong possessive man and still have control if she knows what to do. Like with my David, he'll tell me what to do and what not to, in order to protect me, so I respect that. On the other side, he's a complete softie, and wont do a thing to hurt me. He's do anything to keep me from crying, and if he causes it ((on those very rare occasions)) he'll immediately apologize and wont do it again. My power is in this desire of his to keep me happy, I know if I beg or get sad he'll cave in eventually. ((But word of advice, use this too much and they'll catch on very quick, so this is an emergency control, besides it's not good to manipulate people too much.))