Manuscript and Information Control

I have just been reading a most fascinating book by the historian Eamon Duffy entitled Marking the Hours: English People and their Prayers 1240-1570 (2006, Yale University Press. It is about books of hours, but unlike most other works on the subject, which tend to de oriented towards art history, this book concentrates on the addenda and alterations which owners made to their own books, reflecting their family and social relations, as well as religious change. It shows how a set of relatively standardised texts could be personalised and individualised, creating a multiplicity of variants.
Intriguingly, I know several people who are taking a professional interest in the marginalia of various types of medieval manuscript books, as study of this aspect of manuscript text reveals a great deal about the attitudes of the readership, and how it changed over time. It is all part of the medieval attitude to text, in which the content of a book is not determined rigidly by the operator of a printing press. Comments, or glosses, written by medieval scholars became incorporated into the formally copied text of various kinds of books. Added text was not vandalistic graffiti, but a legitimate expression and a valid use for a book.
I have, on previous occasions, indicated various ways in which I think medieval manuscripts more closely resembled modern web sites rather than printed books, and this is another example. A page of manuscript text was not regarded as final, absolute or inviolable, and texts could evolve through commentary and discussion, a bit like a blog. Given the anxiety that authorities, who think they have a right to control our opinions, are expressing about the availability of information and opinions of diverse kinds on the internet, does that lead us to surmise that the great advantage of the printed work over manuscript in the late 15th and early 16th centuries may not have been so much technological improvement as more authoritarian control of text?