Most people here are aware of the book "Looking for a Challenge", a collection of the best problems from contests organized or co-organized by the University of Warasw. I think it would be a nice idea for Codeforces to write a similar book including its best problems with high quality tutorials, Codeforces can make money by selling it and users will be happy with the problems.
I think the main benefit of such a book would be highlighting good old and not very popular problems, and offering an educational tutorial that can help users deeply understand them.
The same suggestion goes for other platforms with a big archive of problems like Topcoder and Opencup, and maybe non English platforms that have a collection of good problems.
I would be interested in hearing your opinions.