Why is the topic of book wringer important?

It seems you might be asking about "book *wringer*" but that term is not widely known or used. It's possible there's a misunderstanding or a typo.

Could you please clarify what you mean by "book wringer"?

Perhaps you are thinking of:

* Book binder: A person or machine that binds the pages of a book together.

* Book press: A tool used to flatten and press the pages of a book during the binding process.

* Book reviewer: Someone who writes critical analysis of books for publication.

Once you clarify your question, I'll be happy to help you understand the importance of the topic.