Publishing houses and the internet tend to have a very stressed relationship. One reason for this might be the very different approach to information books and internet sites offer.
While a book is historically a closed microcosmos exploring and explaining a single thesis or area of knowledge, the internet offers a plethora of information on nearly the sum total of human knowledge.
It is and was always possible to publish books without extensive internal knowledge of the books subject: A product- or program-manager will contact and contract an editor, the editor will find authors and coordinate the writing. As long as the editor has a „good name“ and the result is sound, the publishing house will be able to sell a book without knowing its precise content.
Imagine the result: a portfolio of monographies not connected to each other in any way. Nobody knows, if multiple books contain identical pieces of information, maybe the same law-texts, same or different commentaries, nor if those pieces of information are accurate or up to date. More appalling – nobody is able to cross-reference these texts, nor cross-sell these cross-references. You kind of get an archipelago of secluded islands of information in a backwater – or backlist – of the vast information ocean.
The internet started as such a secluded thousand-island backwater until the advent of search-engines. Search engines made the wealth of information contained in these secluded – sometimes obscure – sites accessible to anybody who cared to key in a search. Information was to be had at your fingertips on a keyboard, cross-referencing was immanent in the ranking of the results or explicit in hyperlinks included in the information itself.
Nobody pretends, that the blogosphere or some fanzines on electronic media cranked out by self appointed „specialists“ are nearly as accurate as a well written monography or an article in Nature run through multiple peer reviews. What remains is the easy accessability, hyperlinking and searchability of electronic bits, pieces and articles.
The internet was never intended to be not linked together. As an author in 1995 you might have omitted a related site in your linklist, this connecting is now done by search engines. So in the end you contribute your bit of information to a vast theme cluster made accessible in the worst case only by said search engines.
Book publishers have to do this on their own. Content – copyrighted, not publicly accessible – has to be read, understood, cross-referenced, cross-indexed and generally understood. The many black boxes outsourced to as many editors have to be opened, assessed and connected into one electronic piñata. Only knowing what you have got in your portfolio will enable you to find it for and sell it to your valued customers in the years to come.