I'm not saying it is some flawless metric that is 100% fair. For example, if you haven't missed a payment for 7 years, doesn't mean you will never default on your loan. Just as a group, people that haven't missed a payment in 7 years are maybe 20% less likely to default, so they assume you are roughly 20% less likely to default. Similarly, maybe looking at all their customers, maybe all claimed facebook math majors on a whole are 5% less likely to default, so when looking at a potential new loan, they could potentially take that % into account for calculating their credit score.

In terms of having a "reasonable expectation that it will be taken account", that's just because it will be a new metric. When credit scores were first introduced and used on-time payment history, people probably didn't have a reasonable expectation that that would be a factor in determining their credit history.

Again, I'm not saying I like this or think it's a good thing for consumers, just that it's likely valuable metric to creditors evaluating someone's credit trustworthiness.