I used to think that.
After what happened to Joe Wilson when he won the primary and the GOP launched a write-in campaign for Murkowski I'm not so sure any more.
Practice makes perfect. The primary system itself needs to be reformed. Then it works better.
Louisiana [for example] requires an actual majority vote to win. And states could also stop crossover votes during primaries. I don’t know the specifics, but primary reform is the key to empowering the voter more.