It was meant to be a simple example to illustrate the point; reality is never that simple. I work in a manufacturing firm and your pessimistic - and just as simple - example is also not quite true. Often, in cases such as this ( where increased automation leads to greater productivity), we redeploy workforce to other positions; extra capacity leads to driving sales to monetise that ability to manufacture more. In my time with my current firm (seven years) no one has been laid off because of increased automation - in fact I can think of at least one line that has seen standard operators up-skilled to become accredited technicians for the new equipment.
Perhaps you should be less cynical and actually read opinions that challenge your blinkered point of view.