There was a time not so long ago, that father son was free to allow a romantic heritage tradition. Dad played a game for a club, that club got the bonus fairy story of his son being allowed to carry on in the fathers footsteps.
Then they re - manufactured the criteria to 100 games played for a club as the flogs in suits felt a need to manufacture an earned history of longer term career standing.
Then they decided this still wasn't a suitable criteria because the game was all professional and there should be minimal advantages or preferences granted to anyone. So they decided to start allowing any club to pick father son kids with a pathetic 20% discount allowed to the F/S club while also allowing bastardised rules for academy zones ( developing juniors phhht ) or kids that have a parent born overseas even if the kid has lived in OZ virtually all his life.
Money n marketing rules over history and tradition every time as far as corporate footy is concerned, more's the pity.