Thought question for the day: if the United States truly afforded a libertarian environment for all, wouldn't we LDS currently be living in Independence, Missouri, and still openly practicing celestial marriage (as defined in section 132 of the D&C, meaning polygamy)? Would this not have been the desired result? If so, shouldn't more latter-day saints be willing to examine the libertarian polital viewpoint more seriously?
First of all your premise that the LDS church would still me headquartered in Independence Missouri, if we had tolerance of religion could be argued as a possibility. There are other possibilities here too. One of the more profound is that slavery would have come to a natural and peaceable end rather than won by bloodshed. This would have affected the LDS church profoundly too since the LDS church and their more than civil way that they treated Africans and Native Americans brought about much of the persecution that the church had to endure.
Now the polygamy question. Even at the height of polygamy in the LDS church, no more than 5% of all males in the church were called by the leaders to enter into marriage with more than one wife. Even then, such marriages were only with the consent of the first wife and the leaders of the church. Polygamy did not come about because of marital infidelity, to the contrary, those that did not honor their marriage, were not even considered for taking a second wife. Given the amount of LDS males murdered or killed by the harsh climate of the times, the 5% number matched quite well with the LDS female population. In today's times such a figure would be far less, because the need is far less, if at all. IMHO.
But as you know, Gods' wisdom often is tested by men's little understanding. Even before the onset of the most bitter persecution of the LDS church, Smith and other leaders knew that such times were coming and foretold of the exodus from the United States into the mountains. This to be done to fulfill both modern and ancient prophecy.