Roger, you said "My main point is that "our" indexing process does not seem to involve obtaining the agreement of the contributors. When the issues here - like whether a thread is combined into one - left as the poster made it - or have a link to others - are largely a question of personal taste - as Jon's post indicates..

It is a logical point, but not a practical one, for the same reason that libraries do not obtain the authors' or publishers' permission when they index their material, but they do the indexing according to their own, often arbitrary rules. But we live with that, even if sometimes you find Terry Pratchett variously under "Comedy", or "Science Fiction", or whatever. If the author or publisher feels strongly about the indexing of their work, they can complain and in some cases (not always) effect a change. Most importantly, nobody accuses the libraries of high-handedness for this practice.

If we can live with this practice in the more important world of books and libraries, I contend that we can certainly do so in a web forum.

Your point would be good for a perfect world, where there is ample time to take care of details. In the imperfect world we are landed with, we compromise, because life is too short for the alternative.