Because there&#x27;s a huge amount of paper you might want to keep. And storing paper costs a lot of money.<p>It takes up a <i>lot</i> of space, and has to be kept dry within a reasonable temperature range. Academic libraries spend tidy sums on climate control to keep their books from rotting away. It also has to be indexed and filed so it&#x27;s possible to find what you&#x27;re looking for.<p>If you do it properly, you end up with something like this:<p><a href="http:&#x2F;&#x2F;www.nationalarchives.gov.uk&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.nationalarchives.gov.uk&#x2F;</a><p>So the costs are non-trivial. And most people would consider library loan records trivial information. So there are good economic and practical reasons for throwing them out.<p>Besides, it&#x27;s unlikely Plato, Jefferson, or Tesla did most of their reading in libraries. (Karl Marx did, but he was probably an exception.)