Here is the Arizona Forward Party argument against Proposition 133 that appears in the Publicity Pamphlet for the 2024 General Election (p48):

The Arizona Forward Party is urging you to vote NO on Proposition 133.

One thing that most Americans can agree on is that our two-party system of government is broken--fostering political polarization and leading to legislative deadlock. Our elected officials care more about preserving the control of their party and finger-pointing than they do about solving problems that are important to Arizonans.

The Arizona Forward Party believes in a vibrant democracy and that all qualified candidates should have equal access to the ballot. This measure will impede moderate or independents candidates from fairly competing for your vote. In order to reduce polarization and increase representation, it's crucial to ensure that voters have a multitude of options.

Our current primary system puts the decision of who appears on the general election ballot in the hands of 10% of each party who tend toward the political extremes. The best way to solve this is to reform how we conduct our primary and general elections to give voters more choice.

This constitutional amendment will forever enshrine our current primary system, and prevent any future possible reforms. If this passes, voters who want to see change in our political system will continue to have restricted influence at the ballot box.

Please vote NO on Proposition 133 to protect your right to make changes to improve our election system.

Why should we care?

Our Founding Fathers realized that our democracy isn't perfect, and gave us the right to modify how we hold our elections. As Thomas Jefferson once said "As the circumstances change, our institutions must advance also, and keep pace with the times”.  In fact, the primary system that we have today was the response to the highly polarized and dysfunctional politics of the late 19th century.

Unfortunately, the two legacy parties have perverted the primary system over the years to make elections non-competitive and only allow the party-endorsed (and increasingly extreme) candidates to appear on the general election ballot.  This system works for them--which is why this legislatively referred proposition is on the ballot.

A constitutional amendment that would disallow any future change to our election system is a direct contradiction to the intent of the framers of our Constitution.

Resources:

Ballotpedia.org summary of Prop 133

Forward Party position on open non-partisan primaries