Librarians rarely do either of these therapeutic exercises.
You can delete a pdf, which is far more difficult to achieve with a
physical book.
The only drawback I can see is that it's harder to scribble notes
(though I understand this can be accomplished by users who know their
way around a computer better than myself). Against this little problem,
it's far easier to extract a section or chapter to keep while discarding
the rest, saving further on resources for storage and streamlining
retrieval.
But the greatest advantages for works such as Préhistoire des Capétiens
II are in vastly expanded size - almost unlimited without extra paper,
printing, binding and shipping costs - and in the opportunity to update
and correct as necessary with free resupply of amended files to purchasers.
Since many authors have a weird expectation of profit from their books,
so that they resist open access online, the much higher rate of return
to self-publishers is an added benefit.
And of course the planet isn't made to groan over each new title.
Peter Stewart