Patronising “helicopter” librarianship can affect their resilience, self-esteem and pride in their heritage.
More than five.
Former university librarian here (now retired). In my entire career, I never met or heard of a librarian who behaved in the comically villainous way you describe.
At one point in my career, the library building I worked in was running out of shelf space for books (we were well past the 2 million volume mark at that point). In desperation, we asked the subject librarians to review the collections in their areas and identify duplicate copies that could be weeded. In many cases we had three, four, even five or more copies of some books. They didn’t even want to do that; it was like pulling teeth to get them to part with Copy 6 of something! We eventually added a sub-basement with high-density shelving so we could keep everything. Someday they’ll probably have to spring for a new building or go to offsite remote storage.
Irishman’s post is right on point. Not every library can, or should, keep every book they’ve ever acquired. There are plenty of academic and archival libraries endeavoring to maintain comprehensive collections; it would be unnecessary, impractical, and stupid for a neighborhood public library or small college library to do that.
I don’t know how many books there are, but I bet half of them are “The DaVinci Code.”