If for some reason you truly can’t afford it, that’s your out. Examples: parents own a business, the NPC doesn’t predict aid reliably, but the kid is a great candidate. Or something happens to family finances in the interim. The family decides if aid is enough. Why do you think it’s just the student?
Not sure why everyone says it dooms the high school. Black listing (I’d call it grey, some muted enthusiasm for the school’s products) might be more when there’s a continuing record of kids who don’t matriculate in any round. Or kids who have issues with academics, behaviors, or a record of transferring out. Not just because some kid can’t afford it.