While it may be extremely effective, I don't think the way you prevent forest fires is to outlaw trees.
That's a silly comparison.
Prevention of forest fires often
does involve prohibitions against, for example, unattended camp fires, etc. And reasonably so. In any event, the forest fire comparison was one dealing with causality relationships. Trying to transfer the comparison to legitimizing government action is a logically inappropriate equivalency.
It is not the place of the government to decide whether people are not making appropriate decisions. So long as we are talking about competent adults, they can make their own mistakes.
But the government
does have a legitimate interest in seeking to prevent harmful social trends. A male dominated society would do substantial harm to approximately one half of the entire populace, and it's perfectly reasonable for the government to prohibit behaviors and social institutions that would contribute to the same. Personally, I think that if a man wants multiple wives it's better to let him have it and let him hang himself with his own rope. But it's perfectly reasonable for the government to disallow it.