In the end, the real effect of such “PUMAs” was negligible at best. Clinton supporters then overwhelmingly voted for Obama, or did not vote. They did not vote for McCain. Palin helped ensure that outcome, to be fair.
Emerging “Bernie or BUST” types, which much seem louder, more obstreperous, and more numerous than in 2008, could be seriously damaging, comparable to Nader voters in 2000.