Again, one at a time, various players could go to various boards and make the identical argument. Not as some plot to make Vancian magic the only system out there, but as individual expressions of personal choice.
"I want Vancian magic to replace GURPS' magic system, but only GURPS- the other RPGs are fine as is." posts one over at SJG.
Then someone else goes over to Palladium boards and suggests that Palladium RPG needs to go to a Vancian casting system, because they'd like it better that way.
Etc. Etc. Etc.
This is not an assertion that Vancian magic should be ubiquitous- I wouldn't want that at all. Rather, it is an illustration that D&D players could make the same assertion you just made, but with the positions reversed.