There is growing but still mixed evidence that more “open” and nonpartisan primary systems modestly increase turnout and make primary electorates more representative, but effects on broader democratic health (polarization, satisfaction, governance quality) are generally small and context‑dependent.[1][2][3]
For understanding U.S. elections, this implies primary structure is one lever among many: it can nudge who participates and who wins, and thereby marginally affect inclusiveness and responsiveness, but does not, by itself, transform deeper patterns of polarization, turnout, or satisfaction with democracy.