That's not a failure of the salary cap, in that case: it's a club building something that players want to be part of. The purpose of a cap isn't to make winning random, it's to ensure that rich clubs don't have an unfair advantage over poor ones just by virtue of being able to pay them more.
It's clearly possible to build this type of setup, as Penrith have done so in the past decade or so. The point is to bring through your own players, who are part of a culture and a setup from day one: playing with their mates, in a system they know, with good prospects of success on the field and the right support around them off it. That's nothing to do with the salary cap, it's about good management.