There's a very simple answer. Rodinal isn't sharper than Microdol-X/ Perceptol, just significantly grainier. Kodak and everyone else in the industry with similar levels of R&D ability knew that. They could have very easily launched competitor products if they wanted. Rodinal's main appeal was its longevity and high concentration, rather than ultimate quality or specialist ability (despite the nonsense talked by the stand development crowd, Kodak, Ilford etc all knew/ know far far more about what actual compensation effects are - and commercialised them in products that actually achieve their goals - if used appropriately). The ultimate factor that defined most of the big manufacturers' developer designs was that they had to perform consistently from a contact print to somewhere around 40x (assuming appropriate enlarging lenses), rather than someone worrying themselves silly over developer characteristics for 3x enlargements or fundamentally unsharp Epson-type flatbed scans. Beutler is vastly better at what people think Rodinal does, but wasn't particularly commercialised beyond Tetenal's adaptations - it turned out PQ could do all the relevant things better.