"I haven't seen many 10" deep walls" - probably why they mention it?

Since the garment rod pushes back to almost flush with the wall, it is good for where you may want to temporarily hang your wardrobe while getting dressed, or laying out things that go together so your color blind spouse doesn't embarrass you... It can be put in places where you would normally need/want more walking room, and only pulled out when needed.

This is just a quick example pulled off the internet of where a rod like this may be convenient, depending on your morning ritual. The red arrows indicate where the wall is at least 10" deep. ;)

Why are the escutcheons always round and not rectangular? To fit these in a divider between two hanging spaces it would be easier if the escutcheons were narrower.