The old theory on loss of antique knowledge was:
The ancient books were papyrus scrolls, the medieval scribes only copied the "religiously correct" or otherwise interesting on pergament codices (books) and left the scrolls to rot, as papyrus is more fragile.
Strange thing with that theory is that papyrus does not have a longer shelf life (pun intended) than pergament.
There are few, but apparently a dozen or so rolls of papyrus did actually survive from antiquity to today in libraries and those are still readable after 1500 years.
Also, a lot of rolls have survived in dry climate in egypt and were found by archaeologists in our century.
So it was not a "maintenance issue", but rather one of deliberate destruction.
In 475, the newly founded library of Constantinoble burned down and was said to have contained 12000 titles.
In 560, Cassiodorus was reputed to have the largest library in the world and he had slightly less than 1000. Interestingly, he lived in Italy, not in Constantinople.
This was the age when
Hypathia was murdered by Christians.
Somehow it seems to me that the old way of thinking early christians=good, medieval christians=bad is not exactly true.
More like the opposite.
Reminds me of how they found a roman cave temple on the Via Mala pass in Switzerland unouched since the antiquity and in the burned out temple there was the skeleton of the priest with an iron spike driven up his rectum....
In Saarburg in 1905 they found a tied up mithras priest who had apparently been buried alive.