Or if you’re plugging into a desktop where the ports are vertical

There is usually still a concept of front. Most desktops if laid down would be laying on their right side (so the motherboard & cpu aren't upside down). From there you can still pretty easily tell how the port is oriented without looking.

Which requires being able to see the plug.

As with most plugs that came before it.

They were not externally symmetric

Also the side that has the logo on.