So you are trying to suggest that the laws of diffraction are not accurate, despite the fact that the phenomenon can be seen (first reports go back to 1828), measured, reproduced, and accurately calculated?
I'm trying to say in general terms that most laws are not perfectly accurate. What is often considered to be accurate is simply sufficiently accurate
for the immediate purposes. Heck! We don't even know what 95% of the matter and energy in the universe is made of, despite the recent discovery of the Higgs Boson which has caused great excitement in the world of Physics.
More specifically, the Wikipedia article you refer to contains the following comment about the Airy disk.
The Airy pattern falls rather slowly to zero with increasing distance from the center, with the outer rings containing a significant portion of the integrated intensity of the pattern. As a result, the root mean square (RMS) spotsize is undefined (i.e. infinite). An alternative measure of the spot size is to ignore the relatively small outer rings of the Airy pattern and to approximate the central lobe with a Gaussian profile.
Just perform the test and, if the result seems to add something worthwhile, by all means share it.
I have done the tests. Following Emil Martinec's advice to use a banknote as a test target, I took about 100 shots in 2009, using tripod and LiveView, comparing my 10mp Canon 40D with my 15mp 50D. I took several series of shots at different distances to the target, and different apertures, and paid particular attention to the accuracy of focussing. By varying the distance to the banknote, I eventually found a distance which produced significant aliasing and moire which was clearly visible on the LiveView screen when the target was in focus. I found this method useful because the resolution of the LiveView screen on the 40D is lower resolution than the 50D screen. As a consequence, I was sometimes not totally certain I was precisely in focus with the 40D, unless I used the presence of moire as an indication of 'spot on' focussing.
The results of my tests are quite clear. At F16, the 50D (equivalent to a 38.4mp full-frame sensor) has a very slight resolution advantage compared with the 40D, equivalent to a 25.6mp full-frame sensor. However, I admit that such an advantage, apparent in terms of the greater legibility of the finest text on the banknote, would only be noticeable on very large prints viewed close up.
Nevertheless, if I wanted to make and 8"x10" print representing a 200% crop of a part of the scene as viewed on my monitor, say a rare bird on the branch of a tree, or an interesting geological pattern on a cliff face, I know that I would prefer to use the 50D shot at F16. I might even prefer the 50D shot at F16 to the 40D shot at F8. I posted a comparison on another thread at http://www.luminous-landscape.com/forum/index.php?topic=68359.60
which shows significant aliasing in the 40D shot at F8, yet no better detail.
As a result of such tests, I would be very surprised if the gap between the D800 and the D3 at F16 were not wider and more obvious, perhaps noticeable at 100% on screen.