>MAKE BETTER USE OF THE SUBJECT BOX

Agreed. If many unrelated ideas are floating about in a single thread, then it is courteous, if not imperative to indicate your posts emphasis in the subject line.
As for digression in general - it's just natural. No one (I hope) expects a thread to have to take a certain path, so who's to complain when it winds its merry-morphing way.
That would be like taking a mystery tour, then complaining about not visiting a particular place! :-)