Nominee, yes, President, no.
If Carter, or any other Dem, had done even remotely well in office at that time, they would have won reelection.
Watergate still burned in many brains as being a “Republican” issue. Carter screwing up so bad made a big difference in the final outcome.
Well, if the business cycle brings some temporary prosperity during Hillary’s term, she may get re-elected, too, in an election against “the next Reagan”. That shoots your theory.
Only reason Clinton succeeded was the Republican congress stopped the excess. No Democrat has succeeded economically in modern times, with the arguable exception of Kennedy, who cut taxes and Clinton with the Republican Congress. It’s like the old Soviet Union. Eventually their own system destroys itself.