Well, it should at least settle any claim that OKRs are useful in themselves. They need to be useful to be useful. "Useful things are useful" would make for a very short management book though.

We're also getting very close to a "no true scotsman" argument. If something has been tried several times and the outcome never came out as expected, maybe there's something more to it than that it wasn't implemented completely right. Not everything that's good in theory is useful in the real world.