It's not useless, it's just targeted at a specific audience. Some people only keep cars for 5 years and then get a new car. I buy used cars about 3 years old and keep them for 5-6 years, so reliability ratings over later years is more important for me (which is why I generally buy Honda or Toyota for my minivan/car needs), but it might not be for those people.

Consumer reports has traditionally been good about showing reliability over different stages of car lifetime, but it's been a while since I looked.