Virtually no lens that hits peak sharpness at f8/f11 (usually implies a lens with an imaging circle covering the 35mm/APS-C format size) will even stop down to f64, with virtually all of them the smallest aperture size will be f22.

These chaps where dealing with much larger formats and their corresponding larger lenses typically, the usual rules of thumb you might be familiar with from the majority of digital interchangeable lens systems or 35mm film don’t always apply. f64 would be fine on 8x10, as one example, and was often used on this format.

Now you’re comparing different sensor/negative sizes against each other. Usually ”full frame” (aka 135mm) diffraction starts to affect on smaller f-values (larger aperture) but on larger negative sizes the diffraction starts to be a problem on bigger F-numbers (smaller apertures). On 4x5 format something like f/22 and on 8x10 f/45.

As pointed out elsewhere in this thread, diffraction depends on the physical wavelength of visible light and the absolute, not relative, size of the aperture. f numbers are relative. A really big lens can be f/64 and still comfortably above the diffraction limit.