Even the 737 Max variants are statically stable in pitch, at least up to the stall. The issue that MCAS was intended to address was the handling characteristics

Even the 737 Max variants are statically stable in pitch, at least up to the stall. The issue that MCAS was intended to address was the handling characteristics, again in the flight regime prior to the stall. I do not know whether the airplane could have been certified, as a separate type, without some sort of augmentation, but it seems that Boeing did not think it could be certified under the common type rating that covers prior variants.