It was literally a free library, open to every member of the public.
When we got 24/7 internet it was a game changer, it was like turning on a tap of knowledge on every topic. Of course the signal to noise ratio was higher back then...
For research on most topics, from history to social sciences to particle physics, the books at the library (or available through interlibrary loan) would be plenty recent enough for anyone not already specializing in the field, and such people would likely already have access to at least a college/university library, and likely a variety of academic journal subscriptions (often through said college/university library).
Growing up before libraries had computerized databases, sure, they had ILL, but the books that weren't in their collection weren’t in the card catalog either, so you had no easy way of discovering that a book you might want outside of a library’s own collection (1) existed, and (2) was available through ILL. It wasn't until after the internet was generally available to the public that most public libraries I encountered had computerized catalogs with ILL availability.
Things like arxiv are a step toward that "tap of knowledge on every topic", but the overwhelming feeling I get from most internet content these days (and that includes LLM output) is that it's an inch deep and a mile wide [2]. A good book -- which can usually be found at your local library -- will vastly exceed the quality of what you can find on your own, if only because of intelligent curation.
Maybe I'm just a romantic (or just old), but for me, libraries are still where you do serious research.
[1] yes, I know that many university libraries have a selection of their content on the internet now, but usually this is behind a login, and it certainly isn't comprehensive.
[2] recent example: I've been working through McCullough's "The Great Bridge", and there are frequent occasions when I want to find out more information or see diagrams of what he's describing. The internet is, nearly always, completely useless for this. Tons of content on the Brooklyn Bridge, but it all says the same superficial stuff. Though I will grant that you at least can find some stuff like this now, if you try hard enough:
https://bklyn.newspapers.com/article/brooklyn-eagle-the-brid...
Seeing a shelf of curated textbooks on a topic (eg non Newtonian fluid flow), gives me a feeling of depth. Each book represents years or decades of an authors life. And they condensed that wisdom into a textbook that could be consumed in a semester.
I would love to be a Knuth type character working in library and writing textbooks.
On one hand it seems logical that public domain books can readily be kept in digital form without taking up shelf space. On the other hand, the experience of browsing and serendipity that many find beneficial will be lost.
Being in that space gave me exactly the feeling you describe. Each one is an artifact of years of a person's life, in book form. I guess that's true of any book, really, but it feels particularly acute for something like a dissertation. Every one of those unread volumes was a moment of long-awaited celebration (literally commencement) for a person. Humbling.
[1] I had to pay for that copy, but I digress. It doesn't kill the romance. I'm a sucker.
I think this is an important observation. In the age of the Web, people might not appreciate what it means when your access to information on a topic is sometimes only through outdated sources, which is a bit different than not having access at all.
I was lucky that my mom frequently brought us kids around to multiple public library branches, but I definitely remember a lot of older books.
For example, a book explaining an electric circuits would involve photos of some kind of common household item large cylindrical battery cell with screw terminals, which I have never seen, not before, nor since. And pretty much any book on computers, robots, or electronics would be at least a few years old, usually several years or a decade or more. (This has improved, at least at my current local library.)
Another effect of being exposed to lots of older books is that, although my hair is still not gray, I'll sometimes inadvertently speak with anachronistic, old-timey language that predates me.
With the old public library books, I also got a dose of vintage subtle American propaganda (e.g., freedom and justice are good, and are American; dictators and secret police are bad, and are Nazi/Soviet), though the Cold War already seemed to be ending. I'm programmed to believe that that propaganda was a positive influence, but it's sometimes uncomfortable values, when one sees an overall citizenry that doesn't always seem to have been marinated as much in quite the same mix of programming.
To say language models teach a person nothing is just completely absurd.
All learning materials really work in conjunction. The books I have read give me better questions to ask the models that lead to more books that lead to more questions.
Then layer on top of that the deep research models. It is just an incredible time for learning.
It is (or was?) possible for libraries to build reasonably durable collections of physical books that they can manage as they choose, shelf space permitting (and if not, books can be sold to make space). But as publishing shifts from physical to digital there is no first sale doctrine for ebooks, so they are controlled by license agreements from publishers.