I'm gonna disagree with you on this. Back in the day we didn't have data-loggers, or sensor input/output readings. We didn't have info from the wheel speed sensors to tell us if our tires were spinning or if it was slipping in the clutch. Heck, we didn't even have A/F ratio readings from our wideband O2 sensors to tell us if we were lean or fat on the jets or air bleeds.
Back in "the day" we couldn't send our spark plugs to a tuner in the midwest with a SASE and have him send us back a tune we could plug into our carb.