Two Sense Worth
This is an area in which I have a certain knowledge, as I find the history fascinating. (And, no, I am not LDS, nor have I ever any intention of going that way.)
The many lurid "exposé"s of LDS sexual shenanigans includes Conan Doyle's first work,
A Study In Scarlet, from which many get their ideas of the horny Mormon Elders.
About all of it has as much relevance to reality as several recent pornographic movies and tv serials. It makes for salacious titillation, but the facts are otherwise. Regular, habitual, and religio-socially sanctioned sexual liaisons can not be considered "libertine" by definition. In West Africa, polyandry (one woman married to several men) is an old and normal custom. It becomes libertine in nature only when the sexual contact is made outside the marriage.
Since the multiple-partner marriages of the old LDS, pre Wilford Woodruff's announcement, were sanctioned -- and in several cases, ordered -- by the church and the society, they cannot by any stretch of the imagination, be considered "libertine" in nature.
The OP is evidently bemused by this popular picture. It will not do to blame the regular LDS for the sins of the FLDS. (The regular LDS have other problems, not pertinent to this thread, which I shall not address.)
So far as the particular social culture of the Mormons, it was inevitably in conflict with the surrounding milieu, from economic problems in Ohio, to slave-owning Missourians, to social clamor in Illinois. While it is true the proximate cause of Joseph Smith's death was the suppression of the newspaper which dared to expose polygamy, the larger picture lets us see the Mormons were too successfully competitive for comfort for their Illinois neighbors.
Leaving aside questions rising from the survival of Hiram or Joseph or both, the group had to go somewhere, and that far, far away from neighbors. They thought they had found it in Utah, only to have the United States catch up with them before they were quite settled in. (They might actually have done better in the still sparsely settled Western Provinces of Canada.) But so long as they remained in North America, conflict was going to happen.
Nor is it a matter of religion or social practices. I believe ANY bunch which were as cohesive and mutually-assisting as the Mormons would be seen as an economic threat. Perhaps under conditions of ghettoization, the particular social practices could be preserved for some longer time, but more likely is that Mormons would suffer the same reaction as European Jewry before 1945.