Washington (CNN) To understand just how big a deal Fox News' decision to part ways with Bill O'Reilly is, you first have to understand this: O'Reilly was the front-facing spokesman for the modern-day conservative movement just as now-deposed Fox boss Roger Ailes was its behind-the-scenes architect.

For the generation of conservatives who came into their political prime from the late 1990s through, well, today, O'Reilly was a North Star of sorts. He was a clear break from the intellectual stuffiness of Irving Kristol or William F. Buckley. He was a tough-talking populist, willing to stare down the so-called "mainstream media" and skewer political correctness.

What O'Reilly and Ailes built was something that not only succeeded beyond their wildest dreams financially speaking but also had a profound impact on how conservatives thought of themselves.

Yes, lower taxes and smaller government still mattered. But populism, wariness of elites and a deep and abiding distrust in the mainstream media also became core tenets of modern conservatism as imagined by O'Reilly and Ailes. Democrats became the party of Hollywood and elites -- in the media, in business, in entertainment. Republicans were the ones fighting for the little guy who felt left behind and scolded by those very people.