Some of y'all bass fishermen are funny dudes.
Deer hunters pass on young immature bucks so we can shoot and eat the big trophy bucks, fishermen eat the young immature bass so they can catch and release the big trophy bass. Weird.
Nobody shoots a trophy buck strictly for the meat. Does and young deer typically taste better.
And the premise is exactly the same...you'd never catch 10 pounders if everyone kept the 6's and 8's. Just like you'd never shoot a 160 class if you always killed the 120's. It's a management strategy just like deer.