> Whenever you go and read a book from your library, you librarian doesn't keep a profile of who you are and judges your value based on what books you read.

Are you sure about that? If you're not in a super-large library with full anonymity, your librarians will definitely know when you're reading a lot of books that suggest some ideology. They may not keep a profile written down, but they definitely will remember. And they do keep a list of books you took home, at least our local library does.

Regarding new ideas: might be different in other places of the world, but public libraries over here aren't that well stocked and feel like they primarily offer what the librarians value (which will largely mirror the mainstream opinion of the general population, as they're state employees). That's different for university libraries, which do keep a more diverse collection.