Actually, your analysis is at least partially true. The Greeks tended to separate the practical from the theoretical. Scholars were looked up to, but working with your hands to actually build things was manual labour and put you on a lower footing. So the people who built such an object would not have been scholars, with an audience for their written works. They would have been people bucking the trends of their times, probably artisan craftsmen.

You don't start to see widespread literacy until after the printing press for several reasons, and availability is only one of them. There was also the class system that gave knowledge only to the upper crust and the priests (who were often interconnected.) Mass literacy was not common until the nineteenth century, and functional literacy as we define it today is very, very new - like, within the last fifty years.