The only reason it's not the case in this example is because computers at the time were a tiny early adopter niche, which massively multiplied and expanded to other areas. Like, only 1 in 10,000 businesses would have one in 1950, and only big firms would. Heck, then 1 in 100 million people even had a computer.
Today they've already done that expansion into all businesses and all areas of corporate, commerce, and leisure activities. Now almost everybody has one (or a comparable device in their pocket).
Already cloud based systems have made it so that a fraction of programmers and admins are needed. In some cases eliminating the need for one altogether.
There are tons of other fields, however, more mature, where increased productivity very much equaled job loss...