Quote:...And because the AF misses are due to different wavelengths focusing differently, and lenses do not have the same aberrations over the whole focus range and even less so over the whole zoom range, AFMA is even less helpful.
By listing more and more reasons for indirect DSLR AF failure, this does not mean that AFMA cannot help to mitigate the errors.
Wavelengths or not, look at a FoCal table like "reliability of AF" to recognize the general flaws and the general tendency of try and (often) error - in the same perfect conditions, constant lighting with enough brightness, no flicker, camera on tripod, AF-S and always the same direction of turning the focus ring away from the last position, there's no chance to come close to 100% reliability - not to mention difficult lighting conditions in terms of quality and quantity of the available light. If you want to ignore these facts, it's helpful for sure to use lenses starting at f/4 - with them you can stick longer to the idea of superior AF in DSLRs.
As to reliability of AF: how long did the designers and engineers had to work to come at least to a certain reliability in a narrow center area of focus points - and how long did it take Sony to come out with the α9, nearly fully covering the image area, nearly no blackout at 20 fps?
Yes it's boring to read always the same advantages of mirrorless, which is not a temporary hype like Lytro or Lomo or milky way pictures are or have been. It's a simple evolution, cutting away the disadvantages of looking in a mirror before taking a picture. And it's no more boring than to hear or read all the lame fairytales about DSLRs as better systems, meanwhile reducing the benefits to just OVF. Which, after all, melts down to not consume a lot of energy...
Current example: Yesterday I had troubles to AF in broad daylight with the D850 - using one of the upper outer focus points and a Tamron 100-400/4.5-6.3. Why? Because I used one of the focus-points which are no cross-types and which are limited to f/5.6! As soon as I zoom back from 400 to 250 mm (and the aperture just switches from f/6 to f/5.6) I can AF perfectly.
Do I need to mention that none of my Z bodies has the slightest problem to AF this lens in the outermost corners?
In my experience, AFMA is very helpful but not a medicine to the conceptional disadvantages of an indirect AF-sensor. And daves "80% of lenses need it" is also my experience, maybe even more, I only recall two lenses out of 20 with no need to AFMA.