DocBook XML publishing might be done in a well-staffed publishing house. However, OOo or LO just does not possess neither the manpower, the time, nor the expertise to do that.
As I said, a DTD file merely provides rules for structuring a document, but does not format it. Somebody has to create a formatting file and also a template based upon the marriage between DTD and the formatting file. It is not an easy, straightforward task.
Doing some small DocBook (XML) programming and formatting with very simple files would help one to grasp the work that needs to be done, though. For that, confer the Sagehill link for documentation on how to go about that. It would be good training in the event somebody wanted to ever go that route. Personally, if I were to go the DocBook XML route, I would employ a WYSIWYG app like FrameMaker instead of apps using a command line and such. I do not working all that hard.
In any event, it is John who wanted to take on the HTML-creation task. He will soon find out that today, one or more CSS files does the XHTML formatting. (I prefer viewing PDFs over most XHTML, amyway.)
As I mentioned before, I will enable the LO Writer Guide PDF for Adobe Reader markup. That would be a good markup exercise for anybody at LO who might want to copyedit it--or proofread it, assuming it is finished. And playing with Comment and Review (analysis) is also fun to do. I will upload that enabled PDF in a day or two.
Gary