Both types of cameras will take equally good pictures on the fundamental principle that the quality of a picture (when intentional) is 99.9% due to the user, not the tool.
It is all about pretension folks. The "must have" features are not really "must have", they are just things to make you feel superior to "amateurs".
Whatever you need to believe to help you feel better about yourself, it's all good. But your 'fundamental principle' of 99.9% of image quality being due to the user is fundamentally flawed.
What I can tell you as someone for whom bird photography is a hobby...when I switched from a 7D and 100-400L to a 1D X and 600/4L IS II, my images improved significantly 'overnight'. What changed – me as a user, or my tools? Gear matters.
What I can tell you as a father who takes pictures of my daughters' gymnastics events...in gymnasium lighting, getting an action-stopping shutter speed with a 70-200/2.8L IS II or 135/2L requires a minimum of ISO 3200, often 6400 or 12800. When I shot with a 7D, the images were unacceptably noisy at high enough ISO, or motion blurred if I used a lower ISO. When I added a 5DII to my kit, ISO 3200-6400 gave a usable image from a noise standpoint, but the AF system couldn't effectively track the girls. With the 1D X, AF tracking is flawless and ISO 25600 gives usable results, meaning I can get 1/800 s when needed. Gear matters.
Is it possible to take stellar, impactful images with a beat up old Digital Rebel/300D and a nifty-50/1.8? Sure. Just not of the subjects that I choose to shoot.
+1000000000000000000000000000000000... with Neuro
I'm happy with 40D, 60D, 5D II and 5D III IQ, however, I'm much happier with 1DX
until 1DX II of course