Like I said
in the very same paragraph you originally quoted, I just know how to manage my AFK time. I know, from experience, roughly how long it's going to take to go from point A to point B, and appropriately judge how long I can stay away from the computer and return before I reach my destination or fly too far past it.
Unless it's a friend of mine visiting, I very rarely spend more than thirty seconds answering the doorbell.
Why shouldn't I go get a refill on my water while my character is auto-flying from Stormwind to Badlands for the event, for example? Or why shouldn't I go check if my cats' food bowl isn't empty while my character is auto-flying from Ratchet to Un'Goro?
It's time where I would be doing nothing, so why not use it elsewhere?