Because if you have a low credit score, they can still give you the loan but they can charge you more. Much more.
They can charge you a higher interest rate, a larger downpayment, if there are closing costs associated with the loan they can charge you more closing costs.
But they can still give you the loan so basically it is a win/win for them because they get the loan but they also make a lot more money.
But it sucks for you, the consumer.
Low credit scores only hurt the consumer
