It can make them much harder to find and read and not everyone can afford to own every book they want to read.
Libraries exist in part to provide access to the materials our users need and want to read. Additionally we are specifically charged with collecting and offering a wide range of ideas in support of the First Amendment.
I. Books and other library resources should be provided for the interest, information, and enlightenment of all people of the community the library serves. Materials should not be excluded because of the origin, background, or views of those contributing to their creation.
II. Libraries should provide materials and information presenting all points of view on current and historical issues. Materials should not be proscribed or removed because of partisan or doctrinal disapproval.
III. Libraries should challenge censorship in the fulfillment of their responsibility to provide information and enlightenment.
IV. Libraries should cooperate with all persons and groups concerned with resisting abridgment of free expression and free access to ideas.
--from the American Library Association's Library Bill of Rights