Hi,
I wouldn't agree on those issues.
Let's assume that I am shooting with a Distagon 50/4 on my Hasselblad using my P45+ back. That will give me a 49x37 mm image with 39 MP.
Now, I can put the same lens on my Sony Alpha 99, mount the camera vertically and take three shots 23% overlap, this would give me a 49x36 image with 49 MP. Same perspective, same bokeh, but with less aliasing.
Now, I could replace that Distagon with an Otus, Sigma Art or some of the first class lenses and perhaps use with a 36 MP body.
In my shooting, I have not seen those magic differences. But could be I am less sensitive to those differences that may exist than others. In a case, I was showing two A2 size prints to three persons at our camera club and all tree picked the P45+ image. One felt that it was better composed another that it had more contrast. Another friend could not see a difference, nor could I. Making identical prints under uncontrolled conditions can be hard. In the case I mentioned the camera position was shifted slightly when switching between the systems. Weather was heavy overcast and I needed to apply significant local highlight compression in raw processing.
In general, I can see the resolution difference between my 39 MP P45+ and my 24 MP Sony when pixel peeping, but it pretty much disappears in A2-size prints. A1 size and up it is visible.
Sony lenses have round apertures and less green/magenta fringing in out of focus areas than the old (Zeiss) Hasselblad lenses I have. The new H-series lenses by Fujinon are better corrected. There are some "superachromats" from Zeiss for the Hasselblad, but I don't have any of those.
To say short. I would say that MF has an advantage resolutionswise on a single shot. But you could reproduce that image by stitching, using the same focal length or even the same lens. Obviusly, it is very possible to stitch MF images, too. I do it often, as I often stitch two three MF images instead of switching to a wider lens and crop.
Best regards
Erik
At a guess, at equivalent aperture on the open end, the MF lens will be better corrected, as a general rule, dollar for dollar. At the closed end diffraction limits come in to play later with larger formats.
If you're stitching, though, none of this applies. You are using a large sensor in a very literal sense when you stitch.