Perfectly sensible for those who have no potential of achieving more but for others who do have potential it seems rather cruel to lock them out of the labour m

Perfectly sensible for those who have no potential of achieving more but for others who do have potential it seems rather cruel to lock them out of the labour market. Unless an employer is atruistic, they are not going to hire such a person and thereby help them realise their potential because to hire them at minimum wage would result in a net loss.