So, there was an incumbent President who ran for re-election.
He got less than a third of the pledged votes in the primary, less than that the combined total of 2 governors who challenged him.
He won only around 60% of the primary states.
Clearly he went down in flames in the general election.
Oh wait, LBJ won in 1964 by 24 points. So much for that stupid meme.
All candidates who ran in primaries, except of Wallace, who merely tested the ground and didn't win any, were favorite-sons, supporting Johnson.
In California, for example, Johnson was not even on the ballot.
Only few states held primaries before 1972.
Popular vote plurality winner was technically Pat Brown, but he ran only in California. And yes, was Johnson supporter.
Before 1972, there were few primaries and favorite sons, which had minimal effect on nomination.
So HOW IS YOUR POST RELEVANT?