I wish I understood why the state runs a primary election. That seems like it should be the responsibility of the party to decide who their nominee is. Should be their own rules, and cost
On the other hand, IIRC my history, before maybe the 1970s the U.S. parties did use more private processes, selecting candidates in the 'smoke-filled room' (the image is of fat old men smoking cigars and making deals). Some say the quality of candidate was better then.