"No benefit to a viewfinder": I hope you are kidding.
Ever tried to use a 600mm or a macro without tripod only using the screen to focus and frame?
Not with the 600/4 (except on a tripod). But for macro, yes...frequently. In fact, I don’t think I’ve ever used the VF with my MP-E 65, and only rarely with my EF 100L. For example this shot with the MP-E 65, which was taken with the 5DII in Live View at 5x magnification with the front of the lens shoved into a bush:
Before the R and R3, I would use the Angle Finder C with my 1D X for ground-level macros, I suppose that counts as using the VF (although it's a magnified view). But with an articulating screen, even that is no longer needed and almost all of my macro shooting is on the rear LCD.
As a relevant side note, at 5x magnification and f/16, the effective aperture of the MP-E 65 is f/96. Under most ambient lighting, that means the optical viewfinder is essentially black and therefore useless for composition.