Why are juvenile offenders' records sealed?

Most states in one form or another basically seal the records of juvenile offenders when they turn 18. These records are also exempted under the public records act for whatever reason it is that they decided to exempt them. So with that above, why are juvenile offenders' records sealed upon turning 18 which allows them to gain employment, housing and other services without the fear of having their criminal adjudication detected? These statements following cannot be the answer because they are not correct: 1. juvenile offenders recidivism rate is higher than adult offenders, so you can't say factually that juveniles don't repeat so that's why they get a break; 2. rehabilitation is statutorily construed liberally (in case you don't know that means the state is not required to rehabilitate those whom it imprisons) so juvenile offenders are not being rehabilitated but instead just housed; 3. juvenile sex offenders have the same basic reporting procedure as adult sex offenders (meaning they must register and that means post cards with their picture in the mail); 4. they are what, developmentally disabled due to their age? If that's the case then the majority of adult offenders would be legally disabled under the ADA since the majority of adult offenders offended when they were juveniles. So, any input, thoughts, whacked out suggestions....let's hear em