Note: I'm a Trump supporter but at least I understand (and have understood for 30+ years now ...) the rules by which a candidate wins primaries and the nomination.
Having said that, the "delegate" system is ripe for corruption and manipulation by the respective political parties rules committees as well as the state committees and that's where the corruption exists. What we are seeing is not a system that's "rigged" for one candidate or another, but a MANIPULATION of that system by corrupt politicians and party insiders.
The delegate system is outdated...as is our Congressional system...ie...all of Congress power is concentrated in DC, where lobbyists arrive with baskets of goodies to “influence” the Congresscritters. The delegates system is concentrated among those who can buy their way with money and time into it...yes, I know it’s the Party...but, today’s working class doesn’t realize this, and I’ve never seen an article or ad for “delegates wanted placed by a “party”