Moderators can split threads. I.e. there is already a function.
I was certainly loath to do it too often. The main reason was that often a Split (like a Merge) didn't work and you had done the effort for nothing. The other reason was that I - like I suspect most people - don't use the threaded form of the forums just
the straightforward (posts in order of date) form. This meant that even if you picked a good place for a split, you had no real idea as to which posts (after the date of the Split) would follow with the Split thread and which would stay in the original thread.
The final reason was that you had to think of a name for the Split off thread. In order to do this right you had to re-read the thread and think (and spend time doing both).
P.S. As for regular people suggesting splits, the question is how. I wouldn't when I was in the forums all the time have been too happy with e-mail (in addition to all the thread alerts) "telling" me to do a Split - and of course the Moderator's e-mail address isn't
generally available. But the alternatives are marking a thread as abusive (which when the Moderator does a sweep of abusive threads (perhaps once a month if you are lucky as there is no "show me all the abusive threads in all my forums - you have to do it
forum by forum) would be seen only long after the Split was first valid) or posting a reply in the thread asking for a Split (which most Moderators would not see).
P.P.S. I am despite my sig not (any more) a moderator in the SP 2010 forums.
P.P.P.S (Now that I've looked at the thread you quote). The problem is that people will insist when the Original Poster (OP) has received an answer to his question on adding new questions to the thread. The thread you quote isn't actually as bad as many
because the follow-up question by the new poster was about the same function and was posted in the same time period. Very often additional posts ask totally new questions and are often posted several months or even years later.
When I was still keenly Moderating the pre-SP 2010 forums I tried to get to grips with this by consistently locking all threads where the OP had either marked a post as an answer or had otherwise indicated that he had received his answer. In that way new
questions could not be added to an answered thread. Even that ws only a part solution because in many cases the OP just disappears and you have no idea whether he/she has received his/her answer or not - however locking threads that were not marked by the
OP is dangerous because even months later he might turn up still looking for that answer and therefore I avoided doing it.
SP 2010 "FAQ" (mainly useful links):
http://wssv4faq.mindsharp.com/default.aspx
WSS3/MOSS FAQ (FAQ and Links)
http://wssv3faq.mindsharp.com/default.aspx
Both also have links to extensive book lists and to (free) on-line chapters
