The intention isn't to use it as a desktop. The intention is to not plug anything into the computer (other than the charging cable, sometime) except when using it as a desktop.

Everything is wireless these days. Input devices, audio devices, networking.

You basically only need a cable to charge the thing (with your USB-C charger), for mass storage (where most new mass-storage devices are USB-C devices as well, and if you have a well-used old one you can keep a dongle stuck to it), and for displays (at which point you are in a "docked" use-case, and so you can just use a USB-C dock or Thunderbolt-display-with-dock.)

All other use-cases are so rare or esoteric that you can just put them off until you get home and to your desk.

Or are you constantly balancing your laptop and a USB-only printer on your lap or something?

So as soon as I get up from the desk I should stop using anything USB? Never connect to anything HDMI unless I'm at my own desk? I think that's preposterous. Not to mention, Apple wouldn't be selling very many dongles if this was really how most people used their laptops.

Portable console via USB-A KVM switch. I often do find myself balancing a laptop next to a rack of servers.