So the RINOs depend on Democrat cross-overs to stay in power?
And with the Democrat side of things pretty much sewn-up for Hillary, there will be no shortage of Democrats and swing voters freed-up to influence the GOP side of things.
To keep primaries “open” is to sabotage the conservative movement.
It would be a definite factor in open primary states. Probably no good data to show just how large a factor in any given election. But in states where there is little or no chance of electing a Dim to statewide office, why wouldn't many Dims take the opportunity to vote for the most liberal Republican candidate?
That definitely happened in Mississippi, even though it was in the general election rather than a primary. Plenty of Dims around who'd enjoy making mischief in a Republican primary.