This is a pretty interesting write-up. I must read again when more awake!
"...there are also compelling arguments against primaries. During the Jim Crow era, white-only primaries were one method (among many) Southern states used to prevent Black citizens from exercising political power. Today, white voters participate in primary elections at higher rates than most minority groups, ..."
https://thefulcrum.us/electoral-reforms/democratic-national-convention-2024