68 was sort of a special circumstance, with President Johnson pulling out of the race late, as well as the assassination of one of the leading contenders.
But it also happened in 1940, Wilkie was nominated without campaigning in the primaries, and I don’t believe that FDR competed that year and didn’t declare until quite late.
True but Primaries were only held in 13 states up to the chaos in 1968. Other then that it was all cacuses and state conventions. The whole reason the Primary process became so widely used around the nation was to “reform” the system. The people who pushed hardest for it were the Democrats. To now, after 40 years, suddenly depart from established procedure and over set aside the winner of the Primaires for a canidate chossen by the party bosses is not going to sit well.
The irony of this is striking. That the very people running the Democrat party now, who mostly the same people so engraged in 1968 by what the Party bosses did, are now facing the procespect of being the party bosses this time that do the same things that pissed them off in 1968.