So here's a part of the history you (and many others) are actually missing that will help contextualize this. Make no mistake, I have issues with the primaries too. But this is interesting and may even reshape your opinion.
For over a century we couldn't vote at all on the candidates. They were completely selected by the parties. People actually protested that system saying they had no say in the candidates, and thus the first presidential primary happened in 1912 I believe (forgot the state). It rolled out over the 20th century because people felt it was unfair the party got to select without their input.