Air injectors ARE bost control.
And to say they are out dated it's just bonkers, probably means your tuner didn't know or the ecu couldn't do it, how to program a three term controller (PID)

Having the ecu control the boost levels are the ONLY way I would have it, it's just as important as ignition timing and fuel, so why use a separate controller that does have all the input facts (corrections)

Air injectors are just the actuators for your control system.