As far as I am aware, there is no compulsory license in the United States patent system, so while patents aren't more restrictive of the _spread_ of technical k

As far as I am aware, there is no compulsory license in the United States patent system, so while patents aren't more restrictive of the _spread_ of technical knowledge, they certainly could prevent the _use_ of technical knowledge. So, like, what's the point? Seems like a lacking solution to the problem you propose. 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.