> > What if the computer you want to log in on doesn't have Bluetooth?

> Only if they’re a bit old. Nowadays WiFi chips double as Bluetooth chips on newer platforms.

What if the computer you want to log in on doesn't have a WiFi chip?

It doesn't have to be an old computer; for instance, the desktop computer I built last year uses a wired gigabit Ethernet connection to the router right next to it, and doesn't have (or need) any WiFi or Bluetooth chip.