Editor's note: Howard Kurtz is the host of CNN's "Reliable Sources" and is Newsweek's Washington bureau chief. He is also a contributor to the website Daily Download.
(CNN) -- There was a time, as she emerged from the rubble of the 2008 campaign, when Sarah Palin was the hottest cultural figure in America.
People loved her. People hated her. She had transcended the narrow bounds of politics to become a larger-than-life figure, the woman portrayed by Tina Fey, the mama grizzly from Alaska. Every journalist in the country knew that if you put Palin's name in an online headline or television segment, your clicks and ratings would soar.
Little wonder that Fox News Chairman Roger Ailes rushed to sign her as a million-dollar-a-year contributor and built a modern studio for Palin in her Wasilla home.
By the time word trickled out Friday that Palin's contract would not be renewed, the reaction was a collective shrug. Her moment had passed. And therein lies a lesson -- about the fleeting nature of fame but also about the nature of media commentary.
The exiled-politician-turned-pundit has been a growing staple of cable news. CNN began the tradition by returning Pat Buchanan to "Crossfire" in between his presidential runs. MSNBC is packed with such Democratic figures as Al Sharpton, Ed Rendell and Howard Dean.
And for a time as the 2012 campaign approached, the Fox payroll included no fewer than four potential presidential candidates: Newt Gingrich, Rick Santorum, Mike Huckabee and Palin. The former vice-presidential nominee was both newsmaker and news commentator, staging a New Hampshire bus tour in the summer of 2011 to flirt with the idea of making a White House bid, though it was all for show.
But Palin never quite had the impact of, say, a Karl Rove as a Fox talking head. She became something of a one-note wonder, jabbing at President Barack Obama for failing to deliver on the hope-y change-y thing but reluctant to challenge her fellow Republicans, especially after Mitt Romney rolled to the nomination.
It wasn't clear what Palin stood for. She also reflexively jabbed the media (except for Fox), seemingly more interested in settling scores than driving an agenda. As Palin appeared from Alaska with less frequency, she became less a part of the national conversation.
The future seemed limitless in 2009, when Palin wrote a book that was a monster best-seller and starred in a TLC reality series about Alaska. Her daughter Bristol would become a "Dancing With the Stars" celebrity (though this would prove to be a mixed blessing). And the former half-term governor was a force in the 2010 midterm elections, even while holding forth on Fox.
A low point came after the Gabby Giffords shooting, when some commentators unfairly tried to link Palin to the tragedy by noting that her political committee had (unwisely) put out a map with the contests involving the Arizona congresswoman and other Democrats marked with crosshairs.
Against the advice of Ailes, Palin lashed out in a Facebook video, accusing critics of a "blood libel" and sparking a debate over whether she was likening herself to centuries of anti-Semitism against Jews.
By 2012, tea party fervor had faded, and the GOP had moved on from the Palin era. The movie "Game Change" depicted Palin as a temperamental and ignorant candidate who wasn't much interested in learning. And Fox itself, after parting company with Glenn Beck, edged away from the hard right. During the Republican National Convention, Palin complained one night that Fox had canceled her appearances.
When her three-year deal was up, Ailes offered Palin a new contract -- but at a fraction of her seven-figure salary. It was a lowball offer, and both sides agreed to an amicable separation.
In an interview with Breitbart.com, Palin talks about broadening her audience, saying: "I know the country needs more truth-telling in the media, and I'm willing to do that."
Palin still has a passionate following and can still make news with a single Facebook posting. But for Fox News, at least, her market value had clearly plunged, and a divorce was inevitable.
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The opinions expressed in this commentary are solely those of Howard Kurtz.