That statement is incorrect. It would be perfectly certifiable with additional pilot training. The killer feature was the theory that MCAS would allow airlines to get away without additional training. Practice proved to be quite different, as is so often the case.
Do you have an authoritative reference for that, stating unambiguously that the plane without MCAS would fulfil all the regulatory requirements for manoeuvring stability in terms of stick force curve slope, for example during a wind-up turn?
(I agree, FWIW, that the plane would by flyable, easily in nearly all flight regimes, and carefully in some flight regimes, without MCAS. But that is not the issue at hand.)