As I mentioned last month, Slow Boring in its second year is going to be commissioning monthly pieces from professional journalists. The month’s comes from Rachel Cohen, a D.C.-based freelance journalist who reports on a bunch of policy and political issues. You can follow her work on Twitter @rmc031 and on her Substack.

A casual observer of the long-running intra-Democratic debate about Medicare for All would likely have missed the subtle but important point that today’s Medicare program does not, in fact, provide Medicare as it’s been traditionally understood to all seniors.

Private insurers now command nearly half the Medicare market under Medicare Advantage — private insurance that is currently available to seniors as an alternative to traditional Medicare.

Since its creation in 2003, progressives have criticized MA as padding insurance company margins by overpaying. And indeed insurers love the program because they take in significantly more revenue than they pay out. At one point d…