What they mean is that before Turing, “computer” was literally a person’s job description. You hand a professional a stack of calculations with some typos, part of the job is correcting those out. Newfangled machine comes along with the same name as the job, among the first thing people are gonna ask about is where it fall short.

Like, if I made a machine called “assistant”, it’d be natural for people to point out and ask about all the things a person can do that a machine just never could.