Rear brakes need to be changed while front brakes are good. on 2003 Subaru Forester

I believe front brakes do 70% of the braking, why would I have the rear brakes changed first?

Asked by for the 2003 Subaru Forester
The parking brake is inside the rear brake disc so that isn't even the issue. The front brakes always wear at a quicker rate than the front. Ensure the rear caliper guide pins slide freely and are not binding up.