I completely agree.

Every time I see a digital library service, where you can borrow a book or other media that then is deleted after certain lending period, I can't help but thinking that they are missing the point.

The time-limited lending period used by libraries is a bug. A bug that's solved by technology.

Libraries exist in order to spread knowledge and information. But they can't share their knowledge to everyone who wants it, they physically can't keep enough books or duplicate them in a timely manner. This bug has been fixed by digital technology, and we can duplicate them in a timely manner to anyone who wants it.

But some people insist on keeping the bug, and that they are doing society a favor.