Basically new car is a 100% system and from first kilometer / month of ageing and exposition to elements various items go down the hill. Each car type had its own set of reasons for that, but result was +-same.
V-tech, yo.
This sounds different, and I think it refers to mechanical fuel injection. Several automakers experimented with mechanical fuel injection in the 80's and early 90's, but I think the concept died pretty quickly. It was rather complex, failure prone, and less efficient than EFI.
Thing is, mechanical FI is almost as hard to tune for emissions and economy as carburetors, so electronic control is necessary.
Chrysler offered an EFI system based on the Bendix Electrojector in '58, but the tech was not fully baked, for one thing, the electronic controls were vacuum tubes in an enclosure in the dash; I think there may be one remaining operational '58 Imperial with that system still running....
Anyway, Bendix sold the patents for the Electrojector to Bosch, which a decade later had developed them into the J- and K- Jetronic transistorized throttle-body EFI systems so beloved by Porsche 914 enthusiasts.
Decades ago, I owned an old Alfa Romeo that incorporated a complicated cam system to control the oxygen ratio to the fuel injection system. More complex than your typical 1-dimensional function of a cam, this cam was "two-dimensional" in its output. The cam follower was able to slide along the axis of the cam based on something or another (RPM? temperature?) and the profile of the cam varied from one end to the other. Now there's a pretty wild "mechanical computer".
A mechanic though told me that over time the middle of the cam would wear — a kind of "saddling" — and engine performance (and probably emissions) would suffer.