There was a moment in the second Democratic presidential debate that perfectly illustrated the difficulty of dislodging the media’s comfortable narratives. The topic was health care, and Hillary Clinton and Bernie Sanders lined up in their familiar positions: Clinton defending Obamacare and citing ways to improve it, Sanders supporting a national single-payer plan to guarantee health care as a right and not a privilege. These are the two dominant poles on the Democratic side: building upon Obamacare, or simply overhauling it.

And then Martin O’Malley tried to chime in.

“I really wish you’d come back to me on this on, John,” said the former Maryland governor to moderator John Dickerson. “Because we have found a way to reduce hospital costs, so whenever we come …”

But CBS wanted to go to commercial, so Dickerson replied, “Governor, you’re breaking the rules.”

Dickerson was talking about pre-arranged debate rules against interruption, but he might as well have been talking about the media’s unwritten rule that there can only be two sides to any issue, any question, at any particular time. That’s a shame, because O’Malley actually did employ an obscure yet worthwhile “way to reduce hospital costs” during his governorship, and it’s no small matter. It threads the needle between defending Obamacare and abandoning it, between today’s technocratic system and tomorrow’s vision for national health care. It’s called all-payer rate setting.