That which you propose is the path of The Episcopal Church. The Church has said, "You may" but each Bishop decides what is permitted in his/her diocese. If the Bishop agrees, "You May," each priest may or may not, and if the priest says he or she will, the congregation decides what will be permitted in their parish. (An aside, our last Bishop permitted priests to perform gay marriages, but not within the geographical boundaries of his diocese, and therefore not within their own parishes.)
I think it is a good system, but it is not perfect. There are still many points where decisions made by the national church, a Bishop, a Priest, or a congregation can offend someone, who ultimately decides to go elsewhere. So while it may ward off a formal split, people self-elect to split nonetheless in reaction to decisions made -- made in one direction or the other.
I was one of you for over 50 years and continue to hold you in great affection and prayer. I hope the UMC finds a solution avoiding schism. I also wish it would get there, instead of kicking the can down the road at each general conference while studying the issue further. I suspect delaying resolution is not helpful either.