Thou shalt not copy this scroll without the author's permission? I don't buy it and it doesn't hold ground historically.
Did people not intuit it before the 18th century? It took over 300 years from the invention of the printing press for modern copyright law to form.
Copyright (and patent) law exists and has always existed because it makes political and economic sense.
See Section I, Article 8 is the US Constitution, for example, where Congress gets its authority to establish copyright. Why do they have that authority? To promote the progress of science and useful arts.
Copyright law is a fundamentally different creature than the criminal law that governs theft and, IMO, this is just a reflection of their differing moral status in society.