A big part of the problem is the length of the "primary season" and spreading out votes over the course of several months.

This makes it really hard to sustain a budget, especially for grassroots candidates...but also sets up frontrunners in a big way.

IMO primaries would have a different outcome if they were all held on one day and we limited primary campaign season to like 3 months tops.

I'd say something about superdelegates but the fact is that parties and primaries aren't really a part of the process. People treat the GOP and DNC like they are official government branches when really they are just more like a private club. They let us have a primary. If the bylaws say they can override the primary, that's the bylaws. If people disagree with it, then either the bylaws get changed or a new club gets founded.

The problem, then, is that our voting system ultimately necessitates no more than two major parties. Since the winner is the one with the most votes*, it's very easy for two parties that align on many fronts to actively work against each other...see Ralph Nader in Florida in 2000. And it takes a huge shift to uproot an established party.