And he was right. At that point there was no measurable gain in productivity traceable to computer usage.
In accounting, product design, shipping, material handling, farming, fishing, manufacturing, etc., nothing you see today would be possible without computers.
To people who have spent their careers analyzing business operations, the computer is on a par with the internal combustion and/or diesel engine in its impact on productivity.
For what its worth, I majored in what might be called mathematical modeling (also known as operations research or econometrics) in grad school in the mid 1970's and I happened to be right on the cusp of the introduction of computers for that activity.
Prior to computers, our models were huge and unwieldy and probably prone to much human error. However much they were prone to error, they were used in every thing from military operations, to product design, to manufacturing, to medicine, to entire economies.
Needless to say, when the computer came along, my chosen field of study made a great leap forward. All of a sudden, we could design systems which were only limited by our imagination and grasp of mathematics. And we could virtually eliminate human error by building in checks and balances and parallel systems.
All this said, I would agree with you that the operative word is "measurement" when it comes to understanding the impact of computers on productivity. Volcker is an old fashioned economist and his tools for measurement are probably quite outdated. But that doesn't mean that such impact doesn't exist or is not measurable using the right tools.