Nobody can even come up with a coherent reason for any of these proposals to exist. Even the ISS is more of a political instrument than a real science thing. NASA likes to say its about studying how to help humans live in space, but those results were in decades ago: more than a few months in zero-g wrecks people. So why are we still trying to build old modular Soyuz/Mir derivatives instead of trying to figure out the minimum spin humans need to stay healthy? Because the whole point is to do familiar safe things while providing full time jobs for ground control.