Mormons were persecuted and kept moving west to avoid persecution. As their new settlements became cities, people would get nervous again and push them out. Eventually, they simply packed up and moved west until they were outside of the Unites States (Utah was not a state at the time).
Utah became a state only after Mormons agreed to stop practicing polygamy.
Utah was a literal hell on earth: desert, rocks, salt lakes, extremely remote. Think Roadrunner and Wile E. Coyote. Few Americans wanted it, so when the Mormons pushed their wheelbarrows (no shit!) there, they found no one disgusted enough with nontraditional Mormon family structures to run them off as previous communities had. The Mormons weren't super thrilled with Utah either, but through years of hard work they made it somewhat livable.
Without the mormons, Utah would likely be identical to Wyoming - barren and empty with no major airports, but perhaps an interstate or 2 to get you through as quickly as possible.
