Why did the direct primary replace the convention in most states?

The direct primary replaced the convention in most states to promote greater democratic participation and reduce the influence of party elites in the candidate selection process. By allowing voters to directly choose their party's nominees, the direct primary aimed to enhance transparency and accountability within the political system. This shift also sought to empower ordinary citizens, ensuring that candidates were more in tune with the preferences of the electorate rather than being selected behind closed doors at party conventions. Ultimately, it reflected a broader movement toward democratization in American politics during the early 20th century.