Calculators didn't replace mathematicians, they replaced Computers (as an occupation). To the point that most people don't even know it used to be a job for people.

I say calculators but there is a blurry line between early electronic computers and calculators. Portable electronic calculators also replaced the slide rule, around the late 1970s, which had been the instrument of choice for engineers for around 350 years!

Imho you are underestimating the work of programmers if you compare them to “Computers”

In fact the first programmers were mainly women because they came from a Computer background.