Hi Frank,
I think you will find that the primary use of ADS-B, as proposed by the "believers", was to initially provide ATC with a tool ... to allow them to help us with traffic separation, traffic information and SAR ... and, by the way, not only to replace existing radar, but to add to the surveillance coverage.
The secondary advantage would be to allow those aircraft with ADS-B IN, to receive a direct traffic picture in their vicinity e.g Oodnadatta circuit area.