LogFAQs > #934697591

Political parties are private enterprises, not a government operation. They can restrict the voting for who will represent them to members of their party only if they want.
It sucks, I know.... I'm also unaffiliated and locked out unless I temporarily join a party. But it's their right to do it.

The real problem is that we have a two party system enabled by First Past the Post voting, so the unaffiliated voter has no say at all in who his choices for president are in the general election.
Of course, the two parties enforce this situation to benefit themselves, and even restrict third parties from being able to debate* with the two main party candidates, so... They deserve all the shit they get for locking people out of voting in their primaries.

* The committee for organizing the presidential debates is oddly not a government institution but one run by Dems and Reps. 30 years ago, Gary Johnson's 2016 polling numbers would've been enough to put him on the debate stage. But after Ross Perot managed to make it there and grow his support, the two parties changed the rules and set the bar for entry impossibly high for a 3rd party candidate to ever attain.