You continue to allude that the delegates of the parties do not represent the people of those parties. This is mostly focused toward the Republican Party.
When we look at past elections and candidates, your facts don’t bear out. When former Sen. Bob Bennett (R-Utah) was defeated in 2010, there was an overall feeling in the country to get rid of incumbents, not just from Utah’s Republican delegates. The more moderate candidate, Tim Bridgewater, received the most votes from the delegates at the convention. In the primary election the people chose the more conservative candidate, Mike Lee. The state delegates were more moderate than the voters.
Jason Chaffetz and the incumbent, Chris Cannon, came out of the state convention for a primary where again the more conservative candidate won. Last year the moderate candidate, Orrin Hatch, won at convention, beating Dan Liljenquist and needing less than 1 percent more to avoid a primary. The more moderate Hatch won the primary, mirroring the delegates' votes at the convention. It appears that your statements that the delegates not representing the people of their parties is incorrect when vetting candidates.
There is no correlation between the caucus system and voter turnout. There are ways to improve the caucus system and it would behoove all political parties to address these issues.