How about one of the major driving forces behind this "pop top" business? Registry sets! Yikes.
The TPGs rate people's submitted sets but note that all coins must be from that TPG and no others included. I probably let my pride get the better of me, but thrice with regards to sixpences and shillings (Victoria and George V) and Victoria half sovereigns, I suggested to each poster on one of the chat rooms that possibly I might blow their set(s) out of the water but chose not to party at their end of the pool & of course they took exception. I guess my real point is that there are many coins that are not slabbed or not entered into registry set competition.