A regular topic that often comes out. Whilst I totally agree with you, it is very frustrating when new posters ask a question, we answer it with several contributors and yet we never hear from them again - not even one reply from the originator.
I can hold my hand up and say that I don`t always mark a thread as resolved either. It slips from "My Postings" as I assist others and I forget about it.
By the way, have you finished your survey? click here ;o)