[rwmj]

You're missing that the computer can help, so it's more like a world where everyone is designing their own chairs, and the computer ensures that the chair is constructable, won't collapse, will fit a range of humans and so on, and finally sends it off to the 3D printer.

The accountant example is a really good one: most accountants likely do write their own Excel macros to suit particular customers or one-off situations.