There's no "brand vs. brand" comparison. It really comes down to a "model vs. model" comparison. [...]
True with compact cameras, wrong with system cameras.
It's still true of system cameras. Would you consider a "brand vs brand" comparison to be fair if we are comparing the entry level model of one brand to the flagship model of another? It really does matter specifically which body models you are comparing.
"System" just brings the lenses, etc. into the mix.
Thats a highly constructed and nonrealistic counterexample. You will hardly ever find anybody who discusses "do I want the entry level model of system A or the pro level model of system B".
Also, even if you buy a lower camera of a system today, you might end up buying a higher model of that system in a couple years. So the presence and quality of such higher models is important even if you dont want to buy them right now.
So yeah, a system is really a system. You compare them as a whole. How many lines of cameras are there and how good are they, how many lenses and how good are they, how about other accessoires like flash, how quickly does the company adapt to new technology, do I even think the company will prevail etc etc etc. Tons of aspects you wont have with a compact camera.
For example a person might decide they want a Canon 5D Mark 3 instead of a Nikon D750 because with Canon they have the option to buy the Canon 7D Mark 2 later and have a high performance APS-C camera for wildlife. Or they will go Canon again because their Tilt/Shift lenses are obviously better and Nikon so far shows no ambition to fix that. Or they go with Nikon because they prefer Nikons flash system. Etc etc etc.
My god. Discussing Canon vs Nikon in order to get better photographs is the same as discussing Word vs Openoffice to write better novels.
Offtopic, but for the record: Open Office is now named Libre Office.
Thats because the "Open Office" project itself apparently is now commercialized (despite its name) so a free version was spawned from the last free version, and called Libre Office, and ever since free development continued on that.
Also Open Office seems to be pretty dead. Not too surprising.