That's faulty thinking. Oils like TGMO with insanely high VI's (like 204 or whatever it was) are extremely thin and full of polymer, that's how you get a VI that high. The VI's of base oils are much, much lower, see my recent M1 EP 0w-20 thread.
Per the Mobil blending guides I've posted in the past, VII content can vary wildly depending on blending choices. Whenever folks try to over-simplify this (like you are doing here) invariably wrong conclusions are drawn. A 0w-40, which is a wide spread oil, can be blended using less VII using higher end base oils than a "cheap" 5w-30 for example. Even your average 10w-30, even though you can readily make one with no VII using PAO, isn't blended that way, they just use cheaper bases.