I can recommend a very interesting talk by Professor Eben Moglen, who teach law history and actually read discussions that happened between the people who wrote and worked with the first implementation of the US patent law (https://www.youtube.com/watch?v=LPzpBn-XGxw).
Also, I am skeptical that guilds were historically the major impediment to the spread of technical knowledge. After all, once ideas are lodged in your mind, nobody can unlodge them, whether by force or persuasion, not even your own self.
I would look instead to the historically enormously high cost of travel and book printing. Since people and books are the carriers of ideas (historically, at least; now we have the Internet), this seems like a more direct explanation.