Utah has used neighborhood caucus and convention system since statehood in 1896, as did every other state at the time.
At only one time in Utah’s history did the state depart for 10 years. In 1937, a powerful State Senate President, Democrat Herbert Maw, convinced enough of his colleagues to switch to an open primary. Some wonder if he had self-serving motives. He had had two losses, a US Senate race and also for governor, because the majority of the convention delegates disagreed with his legislative voting record. But he was well known and had money.
Many felt like an open Primary was the ticket to the governorship, and he did win. But the Change in the system only lasted for a decade. After disillusionment, Utah restored the Caucus and Convention System. See the Deseret News from 1946:
Today only seven states still have a caucus and convention system, but Utah is the only state that actually nominates the candidates in the convention that are placed on the ballot. Other state conventions are endorsing conventions, but the party has little or no control over which candidate/s runs against its endorsed candidate and whether the others even represent the Party platform.
The current system does not protect the incumbent, wealthy or famous. I think that is a good thing.
Historical research credit: Cherilyn Eagar