[1] https://en.wikipedia.org/wiki/Licensing_of_the_Press_Act_166...
The Statute of Anne includes the deal of provision of copies on deposit to named libraries, and of entry to the public domain; education and availability of publications are specific aims.
It provides a reward period of up to 14 years (the cost of printing being considerable), and then entry to the public domain making for easy and open competition.
It would be like saying today that a monopoly period of 14 months on a book was inhibiting competition - such a period allows recovery of costs, and so aids the dissemination of literary and artistic works by make it cost-effective. Yes, it inhibits competition, but key to the other aims is that this inhibition is limited in order to provide a genuine, timely benefit to the public.