No you don't. Some garages will "chip" a car, this means either putting new parameters into the existing ECU or, more drastically, putting in a whole new after-market ECU. Nobody makes a living removing the electronics from modern engines.
Yes I do. They go as far as replacing the inlet manifolds as necessary and petrol cars get standard two barrel carburettors. In fact they did it to my Mazda 4x4 and every time I take it in for its biannual Controle Technique I get better than the book value emissions.
I also said that the electronics was/is used for emission control in the first place. This was to meet some 'perceived' requirement and it was thought that it would save people having to take the cars to a garage to be tuned up.
It might run the infotainment at the moment but how long before it becomes required as a backup to the latest EU directive that all cars will call home if they have an 'accident' be it a bump in a pothole or a real accident that requires reporting.