You assume that preferences are economically important. I'm not saying I disagree, but in theory you could have a central planning department that effectively s

You assume that preferences are economically important. I'm not saying I disagree, but in theory you could have a central planning department that effectively says "we have calculated what you need for maximum productivity; here you go, like it or not". That, of course, doesn't take advantage of the sensory and compute power of individual humans. You might not need to ship a new hammer from the nearest warehouse if a nearby hunk of metal will suffice. Or if a machine is broken, you might not need a technician to drive from the nearest city if your niece happens to know how to fix it. Also, for central planning to work, it becomes obvious quickly that people need to do exactly what they're told. Ignoring the preferences of people and demanding they do as they are told looks a lot like slavery. Perhaps a comfortable and efficient slavery, but slavery none the less.