Hmmm. It would take Shimano a number of generations of index shifting to spec out a derailleur mounting tab that migrated away from the Campagnolo standard. Even then it was not much. I think there is a turning point soon though with the changes seen in the most recent mechanisms.

like the braze on shifter bosses, that battle was done with The 7400 group, Shimano adapted to the "Campagnolo" standard. Doing a nice job of encapsulating it.