[gus_massa]

Then what is an useful job?

* There is no need of professional potatoes farmer, because everyone can have a personal (family?) potato plants in the backyard.

* There is no need of professional general doctors, because everyone can look up the symptoms in Wikipedia. (I strongly recommend a professional surgeon!)

Jobs specialization is very useful. For example in a small software project someone can do all the job. But in a big software project usually there are some divisions. Someone does the UI, someone the server stuff, someone the Android port, ... It's not a flat organization where everyone just add code wherever they want willy nilly. Perhaps someone can fix an obvious typo in another part, but for big changes most of the work is done by the official or unofficial owner.

[jbmorgado]

Yes, let now try and mix basic food needs like planting potatoes with you getting the munches at 3 AM and asking for a pizza delivery just because you know there is a service like that available. Whatever wins you the argument in your head, right?