Yea imo, they’ve done too far in their scope. You can’t just put up copyrighted works that are still readily for sale unrestricted like that. The whole library model only makes sense based on scarcity.
I would argue broadening of the scope only increases legitimacy—if the goal is to build an archive of literally everything, any objection to an individual piece of content is of diminishing validity.
And FWIW, I think an archive of everything is an incredibly valuable endeavour we should protect. We've already lost far too much media.
I thought they kept the originals and returned the copies? Plus even if they were copies, the chances that those copies were the only remaining one when it burnt down is pretty high
Barely anything was left in the library by the time it burned down. It's quite a myth that all that much was lost at all. By the time of its destruction, most of its books and knowledge has been moved elsewhere due to decades of reduced funding and support.
Furthermore, the burning did not destroy the entire library. It was a gradual process over a long period of time. What destroyed far more of the books is a lack of care to copy them. Paper and papyrus don't last that long, so the only way to permanently maintain them was by copying them out again. Which is a lot of work.