I disagree. Much of the digital humanities is actually of direct descent from bibliography and textual criticism. I would argue, in fact, that the field of book history owes a great deal TO digital humanities which exposed the nature of the book as a writing technology with unique textual affordances. A large amount of digital humanities work is centered on how to capture "bookness" in the digital realm including digital editions of just about any literary text, the Textual Encoding Initiative, etc.