It's true of almost every public service that it wouldn't scale to handle everyone simultanously.

Suppose that literally everyone decided to check out books from the library: many libraries, especially smaller ones, would quickly become empty of books!

I work from home, and I could work at the library, but I prefer to work from home, because I prefer my home environment to the library environment. I did work from the library quite a bit when my internet was out for a week, and it was a great relief to have the library available. I don't think there's a danger of overcrowding, though, because there's nothing now stopping people from working at libraries, and it hasn't been a problem AFAICT.

The author is not revealing any hidden, top secret fact that nobody knew before.