Diver's experience should be assessed by the number of dives, the hours underwater, the sites dived, the different scenarios seen, the certification level, and so on.
I met a dive instructor some years ago that had only dived in fresh water in a quarry complex (several quarries in cascade). He had no sea water experience. How could he get that instructor cert ?
You think freshwater experience is useless? Divers wreck diving on the North American Great Lakes are probably more skilled than the average tropical recreational diver. Cold water, drysuits, lower viz, etc.