Question is : why is that ?
It’s because clients think that "data is just data and connections from here to everywhere are ubiquitous."
Basically: they aren’t completely wrong, and sometimes - due to their naivety - ahead of their "solution"-providers -

they only underestimate the technical efforts still required.
Honestly: the gap between web and desktop is going to be closed during the next few years. And this will also give a different prospect to what "content management" means.
To come back to my previous post: we’re still using databases to "simulate" documents (MODx does exactly that) - but I argue that’s just a legacy issue. "Content" will get far more dynamic and distributed, and as well as the desktop won’t be able to stay in - not really "splendid" - isolation nor will any CMS-software.
just my 4 cent...
EDIT: the 5th cent/sense: about 2 decades ago (with "dbase III") I got very excited on the "group-theory-like" approach of SQL and all that stuff. Then, due to short-term business requirements, which lasted, helas: 2 decades

I forgot about most of those ideas. Now they come back, stronger than ever, and they hopefully will free us from this document (i.e. paper) paradigm.