The final crack in the traditional convention process came eight years later at the 1968 Democratic convention in Chicago. Minnesota Sen. Eugene McCarthy, who won the most primary votes, lost to fellow Minnesota Sen. Hubert Humphrey in the delegate count. Humphrey had not run as an announced candidate in the 17 primaries, and only 38 percent of convention delegates were chosen by voters in primaries. (Republicans picked just 34 percent of delegates in primaries.)
Both parties soon initiated reforms to ensure that more voters had a direct role in choosing political nominees. In 1976, Democrats selected 73 percent of convention delegates in primaries, while Republicans chose 68 percent. In 1980, the name “Super Tuesday” was used to describe the final Tuesday of the primary season in June, when a key group of states that included California and New Jersey cast votes.
https://constitutioncenter.org/blog/a-brief-history-of-presidential-primaries
The selection of Harris is a step backwards in the democratic process.