Hence the motto of the article: capitalism creates unnecessary jobs.
* There is no need of professional potatoes farmer, because everyone can have a personal (family?) potato plants in the backyard.
* There is no need of professional general doctors, because everyone can look up the symptoms in Wikipedia. (I strongly recommend a professional surgeon!)
Jobs specialization is very useful. For example in a small software project someone can do all the job. But in a big software project usually there are some divisions. Someone does the UI, someone the server stuff, someone the Android port, ... It's not a flat organization where everyone just add code wherever they want willy nilly. Perhaps someone can fix an obvious typo in another part, but for big changes most of the work is done by the official or unofficial owner.
Yes, that's the all point of the article and also the one I explaining: Capitalism is about "maximizing profits" not about social, intelectual, or even productive efficiency.
If someday in the future drone delivery is allowed, and it's cheaper to use drones than humans, then they will get unemployed an no one in the evil elite will drop a tear.
[It's more complicated, because the delivery guy sometimes help with the other activities in the pizza shop while not driving, like cleaning or moving the sacks of flour. So the dismissal will not be immediate.]