More myth, in the studies, swing state voters who voted on economics voted for Clinton, and Trump voter's motivation was cultural anxiety, not economics, just as in other states.
Bernie won Michigan and Wisconsin specifically because he was talking economic issues that resonated with blue collar voters. Bernie didn't beat Clinton in both those states because of cultural anxiety. It was economic populism. If Bernie were the VP nominee, the swing states would have gone to the Dems, and the election wouldn't have been close. The fatal flaw wasn't "Bernie as the nominee", it was always "Tim Kaine, corporate shill as VP", and Kaine was a forgone conclusion as Hillary's VP in the post-Obama reelection.
The economy was the issue in those swing states, and the DNC will never acknowledge it because it exposes their negligence in their ground game by blowing an astronomical lead against their hand picked opponent and their assumption that blue collar labor was a given for Democrats.