This is really starting to get annoying. What I mean by "over posting" is that the question on the topic has been fully answered....but for some reason people continue to post. A recent post that comes to mind is Ricwyk asking whether to buy a digital or an accoustic piano. Everyone gave their opinion on what they thought was good and bad about both types, and then Ricwyk posted that he had decided to rent an accoustic, and that should have been the end of the post, as it had fulfilled it's potential. But the posts kept coming! People continued to tell him what they thought he should buy, even though he had already decided on the accoustic! I could bore you with a plethora of other examples, but hopefully the point is clear--this is just taking up needless space on the forum. Please be courteous when posting and if a post has already been answered to it's potential, then there's no point in posting; if your opinion is exactly the same as someone's that has already posted, then there's no point in posting unless you feel that this opinion needs special emphasis. Remember, be a courteous poster!
I guess I should not say anything, as I agree with a lot of what you say - so the point is made already...

However a) I am probably guilty of doing what you describe myself,
b) it actually has SOME advantages
c) I don't think it is THAT bad.
I will needlessly expand on these points now:
about a) posts often stray from the topic, and then you end up posting discussing this topic even though the original question has already been answered, or is no longer "topical". Instead of starting a new thread, it often seems to make more sense to "keep it in the context", so you can assume all the information present within that thread as known to the reader.
b) more advantages: I read the thread you mentioned. I do not actually care that much whether Ricwyk gets an acoustic or digital piano in the end. It is highly useful though, to have a wide spread of opinions and ideas on the topic of digital versus acoustic (and indeed qualities of various digital pianos) just in one thread.
I much rather read one v. long thread with many quotes/refernces than searching and ploughing through 20 mini-threads, where someone says: I like digitals, end of message...
c) nobody forces you to read a particular thread again and again. So unless we have reached hardware limits - what is so terrible about it?
Egghead
p.s. I have a fast internet connection - is this relevant, perhaps?