Some grade-grubbers prefer to repeat in college the courses that the college allows skipping with their AP credit. If such grade-grubbers are pre-meds, it is better for them not to get the AP credit, so that they do not have to mark “repeated course” on their medical school applications.
There are some colleges that charge more for upper division status. If a student brings AP credit but does not use it for any useful subject credit or to help graduate a semester earlier than otherwise, the AP credit may push the student into upper division status with higher tuition earlier than otherwise.