Originally posted by clackers All that irrelevance and not seeing the wood for the trees didn't involve just cropping and scaling, they 'downsampled' and 'normalized' as well.
You speak of 'downsampling' and 'normalizing' as if they also are special cases. They are not - they are the default case.
Every time you export your raw images to jpeg they are downsampled, and things are normalized. Even if you don't do some sort of export first - every time you send directly to a printer, the printer driver does this as well.
If you're printing at native resolution (or even bigger, and up sampling) then the normalization doesn't occur in the same way, but if you are printing cropped images at the same size as native uncropped images, then you are enlarging the cropped images
more than the uncropped, and you run into the exact same issue.
Again, this describes what you, the photographer sees when you crop and enlarge.
I'm going to keep pointing you back at the core issue you seem to want to sidestep -
unless you, for some reason, want to keep all your crops smaller than the uncropped images in display or print, you will see degradation in both noise and DR in the final image after cropping. No way around that. No way to talk your way out of it.
DXOmark, Bill claff etc describe
how much degradation you can expect. They are not lying or making things up. They did the work and measured the results.
.