Well it’s a theory of course but it’s not easy what they are trying to pull off and there are significant risks which is why it’s being done by proxy. Perhaps 3rd parties were unwilling after those elections or they didn’t see a path thru the courts that made it viable. You also have to consider we have different players here on the losing side - I believe the Clinton / Obama team is much more willing to take risks to advance or protect their perceived causes.
Actually, I would think the opposite is true. Casting a provisional ballot subjects it to a level of scrutiny that isn't given to a normal vote that you cast just by showing up on Election Day and voting like most people do.