OK, I am in favor of an open convention and some real old fashioned horse trading with some serious smoke filled rooms.
The video below is long but will give you a flavor of what used to happen. The Democratic Convention of 1924 pitted the two favorites, Al Smith, the governor of NY against William MacAdoo, President Wilson’s son in law. Before it was over neither got the nod. John Davis, a well known lawyer from New York was nominated only to lose to Calvin Coolidge, the quiet man from Vermont (that was long before Bernie), who was quoted as saying “If you never talk to the press, you can never be misquoted.”
In those days and unfortunately even today the KKK was a big issue. The convention was called a Klanbake
and it was a real barn burner and I for one am ready to see some firewotks in Cleveland in July.

If you look carefully you will see FDR speaking and placing Al Smith’s name into nomination.