Subprime loans are not lending to people who can't repay. It's lending to people who don't have the credit history or have a poor history and giving them a chance to borrow money. If they can't afford the loan they shouldn't be getting it in the first place.
That's a different argument. I'm not arguing the point of allowing them to borrow more than they can afford to repay. I'm arguing the point of allowing them to borrow what they can afford to repay at rates that allow them the opportunity to do so rather than making them pay rates they can't afford for money they desperately need.
Preventing them borrowing more than they can afford to repay is a different and necessary oversight. Nobody should be put into a position of debt slavery. So I agree with your point, I just don't agree with your premise.
By borrowing beyond their ability to repay? That's gambling at best or just debt slavery at worst.