It is not, at all, the same kind of thief or library.

Old books are unique pieces and having them in library make them accesible to the largest number (digitalization being the obvious next step). Stealing them and selling them to private collectors makes them inacessible to the public.

Academic papers are accesible as pdf provided by editors, they can trivially be copied and shared without making the originals less accesible. Pirating them makes them more accesible and does not hurt the public (at least this is my belief, editors hold a different position).

Equating libraries that provide a public service with editors that restrict access to knowledge hurts more than it helps.