Ryan Lizza's long dive into the internal dynamics of the House Republican caucus features an extremely telling anecdote from Devin Nunes, a Republican congressman from California.

Nunes explains that conservative media has grown to a point where it's actively harming conservative policymaking, because the conservative grassroots have become inundated with false information that leads them to put pressure on conservative members of Congress to do things that aren't grounded in reality. Nunes says that these days only a small portion of what he hears from constituents is "based on something that is mostly true":

Nunes, who is the chairman of the House Committee on Intelligence, told me that the biggest change he’s seen since he arrived in Congress, in 2002, is the rise of online media outlets and for-profit groups that spread what he views as bad, sometimes false information, which House members then feel obliged to address. The change has transformed Nunes from one of the most conservative members of Congress to one of the biggest critics of the Freedom Caucus and its tactics. "I used to spend ninety per cent of my constituent response time on people who call, e-mail, or send a letter, such as, ‘I really like this bill, H.R. 123,’ and they really believe in it because they heard about it through one of the groups that they belong to, but their view was based on actual legislation," Nunes said. "Ten per cent were about ‘Chemtrails from airplanes are poisoning me’ to every other conspiracy theory that’s out there. And that has essentially flipped on its head." The overwhelming majority of his constituent mail is now about the far-out ideas, and only a small portion is "based on something that is mostly true." He added, "It’s dramatically changed politics and politicians, and what they’re doing."

Up until this past fall, the main concrete manifestation of this phenomenon was House Republicans occasionally lapsing into tactically counterproductive moves like the 2013 government shutdown.

But Nunes's observation also provides crucial context for understanding the rise of Donald Trump.

Trump has a symbiotic relationship with the most heavily commercialized segments of conservative media (Breitbart, talk radio, etc.). These are places that, on a fundamental level, don't really care about public policy issues or tactically sound ways of advancing policy goals. Donald Trump is a great character and a great story, and many of the stories he tells are themselves great stories. That's good enough for them. But it's starting to impact politics in the real world.