I didn't say that it predated magic, I said that it came about before the idea of turning cards sideways (as "tapping", "kneeling", "exhausting", "rotating") became an entrenched mechanic.
M:TG and Netrunner were both designed by Richard Garfield and Netrunner's design was directly influenced by his experience with M:TG.
Cards in Netrunner aren't tapped because actions in Netrunner are limited by a player's "clicks", not just their available resources.
It was a design decision.