Well, open primaries can be frustrating for the party, but, generally, in states that have closed primaries voters simply switch parties before the cut-off date to vote in the primary of their choice. And states that allow voters to register as Independent gives them the option of choosing either the “R” or “D” ballot; that’s how Virginia does it since all registered voters in Virginia are, in effect, independent.
Why isn’t this in BREAKING?
In a closed primary state, not many are going to go through the time & trouble of registering back and forth between primaries and general elections (and it wouldn't be hard to prohibit such behavior if it became a problem). I moved to VA from CA where, thankfully, an open primary concept was rejected by the voters - one thing CA does right.
Here in VA, an open primary greases the skids for nominating someone the majority of Republicans don't want. This to me is just as big an issue and problem and this signature fiasco.