I'm a little confused how a person can play a 3D video game with just a keyboard, but a website is beyond control? I don't think a car is a good comparison as it is in 3D space unlike a website.
By comparison pages have dozens of links, form fields, menus, etc. It’s not that they can’t be navigated with the keyboard alone, it’s that it’s rarely the most efficient way of doing it. Clicking a link will always be quicker than pressing tab X number of times to select it.
You seem to be under the impression that Netscape style navigation is the best a keyboard can do, which makes the argument an involuntary strawman.
Spatial navigation and caret navigation blow a pointing device out of the water.