Sorry, man, but I humbly submit that you're incorrect. The facts I've presented I can back up, otherwise I would've qualified my comments as being an educated guess.
If you doubt me, as you clearly do, then do as I've done....go to a tire store and compare tires of like sizes, all-season vs. winter tires. Then let me know if you still disagree.
The reason I first noticed this phenomenon is on my 500E. When I first installed 225/55-16 snow tires, I was amazed at how narrow the contact patch looked. And sure enough, compared to my all-season tires they were quite a bit narrower, like an inch or more. Same deal on my 300TE, which I was running 195/65-15 summer and winter tires on.
Further, be advised that tire manufacturers do NOT all make tires of the exact same size-compare for example a Toyo to a Michelin, and I'll bet you a buck the Toyo is shorter but just as wide, which is likely why I have NO rubbing while running 225/50-16 on my TE. As a matter of fact, many of the manufacturers publish their tires' actual dimensions, so if you can find this info on several companies, compare them and you'll see what I'm talking about
Lastly, 205/60-15 was only the "stock" size on factory Sportline W124s with 7" wide 15" rims-all others were intended to run 195/65-15.