I understand that as a voter, I want delegates to be representing the voters. If at this stage of choosing the nominee that doesn’t happen, our “representative form of government” is a farce and a lie.
A fellow over at AT described the process whereby he became a GOP Wyoming delegate. It was months long. It consisted of pitching in, showing up, and being elected in the end by a smallish committee of those who had done the same. It's how it generally happened across the country before there were primaries. Direct plebiscites for national office were never taken in America before modern times. The process he describes brought us Washington, Adams, Jefferson, etc., well into the 20th century.
Primary elections are subject to their own distortions, including people who aren't in the party crossing over to make trouble, distorted ad campaigns, state-run media people who meddle with debates, and voter fraud at the polls.
Locally made systems based on who shows up not only seem as good as primary elections to me, it's clear from reading the USC that for some national office or court to define the form they must take across state lines would be unconstitutional. Ours is a government by agreement of States, not a national swarm of voters on a certain day in time. Our amalgam of local processes is what built America and has preserved it from totalitarianism up till now. It's the worst system in the world except for all the others.