Crossover voting is real in Idaho. Estimates of 15,000 democrats registering as Republicans for the May 2022 primary. This rule was proposed at the recent Idaho GOP convention in Twin Falls and passed. This is not the final form of this rule.
I do understand the concerns of how to implement this. Keep in mind that this is a party rule, not Idaho law at this point. It was an excellent indication of which counties in Idaho that see this as an issue and those that do not.
Here are the counties that voted against this rule:
Counties that were divided on this