That's a valid criticism, but the point is that you can have two types of curvature that you assign different "units" to when measured, but they're still both c

That's a valid criticism, but the point is that you can have two types of curvature that you assign different "units" to when measured, but they're still both curvature. As a hand-wavey example, one could claim that energy in the form of bosons is just a "wiggle"[1] of the spacetime fabric, and that matter in the form of fermions are topological defects or knots. That way they're different enough that you'd want to use different units to represent them, but at their core, they're both distortions in spacetime that must inherently cause a distortion in spacetime at a distance (GR). It also explains how they're inter-convertible. E.g.: energetic gamma rays can be converted into electron-positron pairs. If they're both "made of distortions" then it's like a very strong wave creating a pair of vortices spinning in opposite directions. You can't count the waves (it's smooth and continuous), but you can count the vortices. [1] For the wiggle, imagine taking a huge sheet of cloth laid out flat over a smooth surface. If you tried to put a wave into the middle, the edges of the cloth would be pulled in. Contrast this with the typical view of fields as "vectors on top of a base (flat) spacetime", much like a mathematical function graph.