But they didnt know that until he plays for them. Unless its an obvious coveted talent, usually you have to give them an incentive in the way of co-ownership, otherwise instead of developing you talent for free, they can do it with one of their own.
Dont like co-owns buts the general reasoning with some of them. If its a player you ae unsure about, on wether or not you will keep him, or the minor team dont only want loan.