I don't need to post my level of accomplishment to have a valid opinion on this matter and your level of achievement is invalid as an argument. There is a large drop off in quality between NRL and the state based leagues. The large majority of players playing in those state based leagues are not good enough for NRL rosters.
Some players may have the talent but they lack the discipline and/or application to make it to NRL level. How many times have you heard an NRL player, when asked to name the most talented player they've played with, name someone unknown who they played with/against in junior rep matches? I can remember Robbie and Lenny Beckett (who played NRL for the Panthers, and for the Eagles and Knights respectively) whilst both talented, the most talented of the siblings was the eldest brother Danny. Thing was Danny didn't like to train, and loved the social life too much, so he was never better than a park footballer.
So it is possible that there are talented players out there who aren't in the NRL. The ting is they don't have the desire or will to do what is necessary to be an NRL player.
Hence the adage that the best footballers have usually been identified by the time they reach under 19s football.