The party prevents progressives from winning if they can. Every progressive who has won a primary in the past decade or so has done so despite the party putting its thumb on the scale for their opponent.
Progressives need to earn their votes like everyone else.
It's weird seeing a centrist say that votes need to be earned after they lost twice by acting entitled to votes.
Party leaders get one vote each, just like everyone else. They can't stop leftists from voting. So if leftist candidates want to win, they simply need to get more votes than their opponents.
And if leftists are discouraged by opposition from "the party apparatus", they are going to be devastated when they find out about the massive electoral advantages of incumbency. Incumbents win >90% of their elections!
With all their whining about "party apparatus", frankly I think most leftists don't have the stomach to take on an incumbent. Which basically means they will never win an election.
But nevertheless, if you can submit your signatures on time, then you can be in the primary. And if you get the most votes, then you will win the primary.
If you can't accomplish those two basic tasks, then you are not a good candidate. Even if you think it's "unfair". Step aside so someone better than you can do the job.
That's not an excuse for running corrupted primaries. Unless you like the results, which you do. Up to and including losing to trump.
It's clear that you're happy with a party that doesn't respect the votes of its members enough to run honest primaries. You're just gloating about corruption, which is what I've come to expect from centrists.
If everyone obeys the law, then a primary is not "corrupt". It is a test of how many votes you can get when your opponent is using every possible legal mechanism to obtain an "unfair" advantage.
And that's exactly the same thing that will happen in the general. So if a candidate doesn't know how to win an "unfair" primary then they are destined to lose in the general. They are not a good candidate, and they should be eliminated as soon as possible.