Many Democrats fumed last month when Senator Kyrsten Sinema of Arizona left the party and changed her affiliation to independent. But her decision has at least one good consequence: It makes Congress more representative of America.

After all, “independent” is––per years of Gallup data––typically the country’s most popular party affiliation, with more Americans identifying that way than as Democrats or Republicans. Recent polls suggest that, if the Senate reflected the American electorate’s party affiliations, the chamber would include 35 to 50 independent members. Yet until Sinema’s announcement, the Senate had just two independents: Bernie Sanders of Vermont and Angus King of Maine, both of whom caucus with the Democrats. The 117th House of Representatives had no independents, and neither will the 118th when it takes office tomorrow.

Sinema, who stoked intraparty frustration by refusing to go along with certain Democratic priorities, was widely expected to face one or more primary opponents in 2024. Her declaration of independence will spare her that challenge. And because she says that her votes won’t change and that she will still caucus with Democrats, they will think twice about supporting a general-election candidate against her, lest they split the moderate vote and hand the seat to a Republican.

[David A. Graham: Kyrsten Sinema’s decision is all about 2024]

Sinema’s decision to affiliate with America’s long-marginalized independents nevertheless prompted many angry reactions. “Sinema owes her entire career to the Democratic Party,” the MSNBC commentator Mehdi Hasan declared on Twitter. In fact, Sinema owes her career to voters and her loyalty to all the people of Arizona, whether they voted for her or not. In Arizona, party affiliation is 35 percent Republican, 34 percent other, and 31 percent Democratic.

Rather than being shocked that Sinema, who belonged to the Green Party before the Democratic Party, is changing her affiliation again, journalists and political scientists should probe why so few politicians follow her example. The glaring disparity between the proportion of independents in the population and their numbers in Congress highlights the structural and institutional factors that give Republicans and Democrats an undue advantage. Politicians who join a major party often get help with funding, campaign infrastructure, voter outreach, or ballot access; the political press is arguably biased against third parties; and America’s entrenched parties and winner-take-all method of choosing members of Congress hinder independents from assembling winning coalitions.

I can’t help but suspect that the dearth of independents is contributing to a loss of faith in Congress as a representative democratic institution. An alarming 70 to 80 percent of Americans disapprove of the job the national legislature is doing, Gallup polls in recent months suggest. The branch’s approval rating among Democrats and Republicans has long fluctuated based on which party is in charge, but independents are consistently cool to Congress. This is hardly surprising; one would expect the one-third to one-half of Americans who decline to affiliate with Democrats or Republicans to dislike a system dominated by them.

In this polarized era, I know I’m not alone in disliking how Democrats have used their control of the White House and Congress but also wishing I had somewhere to turn other than the Republican Party. During the Trump administration, I was eager to end GOP rule but wished I had an alternative to the Democrats. Although three independents who all caucus with the Democrats may not be enough of a change to make Congress more popular or less dysfunctional, 10 independent senators could wield real clout as a swing bloc; 15 or 20 independent senators would transform the institution—and offer encouragement to the many American voters whose policy preferences do not neatly align with the Democrats or the Republicans.

[Nathan Kohrman: ‘She made an idiot out of me’]

When the Senate returns to session this week, I’ll be curious to see whether Sinema’s change of affiliation will alter how she does her job. I have no idea whether, if I were an Arizona voter, I would favor her or one of her prospective challengers come 2024. But until independents are represented on Capitol Hill in something approaching their proportion of the American electorate, I’ll see an upside anytime a Democrat or Republican follows Sinema’s example.

David Downes, who paints from his photographic memory, says being autistic has shaped his whole life.