No transfer fees is a massive amount of income some clubs (and NPL clubs) can earn. Teams like CCM can focus on development with their COE and gain income from selling off their players to other HAL teams.
But 10 teams is too small. We need 2 tiers of 16 minimum so there are more places and opportunities to play and sell/buy from. Most of the recycled HAL players will end up in A2 (as you see overseas) where the A1 start buying better players to remain in A1 and fight for the prize money of winning and the broadcast money of A1 (and ACL).
Increasing salary cap isnt the sole answer. It just means the PFA will argue for a new CBA and everyone that is currently a mediocre HAL player just gets paid more.
But because there is no real competition or consequence, it means the same recycled players "with A-League experience" and lack of real intensity in training.