It took longer for a medieval manuscript to be copied than for a printed book to be printed or for an ebook to be coded and uploaded.
A medieval book was more expensive to buy than a week full of cooked meals. Some books today are more expensive than a month-full of ready-made meals.
Achieving literacy in the 9th century was more costly than it is today to buy a villa but the career potential was greater than that of an MBA program.
All the resources of a medieval book-writing project went into production. Marketing came later in the age of universities. Advertising in this period was a mix of authority-buzz-naming and forgery. If you wanted your book to be read, you could cut corners (I’m not talking about trimming your manuscript, which was also common), and use a famous author name for a non-famous text. Not yet famous.
The trick worked. Non-famous texts became popular – and famous. Medieval libraries were filled with pseudonymous works.
Pseudonymous. Apocryphal. Authentic. Genuine. What’s the difference?
If you write a book today and publish it under the name of someone famous (say you could), you’ll called a liar and an impostor. If you were lucky enough to publish your book in antiquity or the middle ages, and the book went on to become popular, then you’re a pseudonymous author who wrote an apocryphal text worthy of study. Apocryphal means the author of the work might be (a soft is) authentic, but no-one cares, because the work’s authorship was widely thought to be authentic. You’d be called a liar perhaps, but a contributor to literature nonetheless. Your text might end up in the university curriculum. In 1000 years, no one will call you a liar, because no one will know your real name. Or care.