>Not because any single task is harder. Because there are so many more of them, all at once.

There's a nuance here since the author says "Almost all of this is private work," but this is basically the entire premise of Cory Doctorow's excellent The Reverse Centaur's Guide To Life After AI, which everyone should read. If I may quote:

>>In automation theory (the academic study of automation), a centaur is a person who is assisted by a machine. Think of a clever human's head, arms, and hands atop a horse's strong body. Riding a bicycle or driving a car makes you a centaur; so does using the mute button on your TV remote when an ad comes on. Wearing a hearing aid makes you a centaur, and so does using a calculator to multiply large numbers. Being a centaur can be glorious.... Best of all, I get to choose exactly which of these features I use.... No one expects me to write more pages when I get a new tool.

[snip]

>>A reverse centaur is a human who is conscripted into acting as an assistant to a machine. There's a classic I Love Lucy episode where Lucy and Ethel are working on an assembly line at a chocolate factory, taking bonbons off the belt and wrapping them in paper. As the belt goes taster and faster, Lucy and Ethel have to work at superhuman speed. They're reverse centaurs: the machine can move the chocolates from one place to another, but it needs a human to pack them into the box, and the humans who act as its assistant are made to work at a pace that exceeds all human capacity until calamity ensues.

"More tasks all at once" is exactly the premise of that I Love Lucy episode.