In my experience in this field, the benefit lies with helping those parents who have difficulty being objective. Understand that this does not apply to every parent. I think I was realistic (if anything, ultra-cautious) about my own children, and I have met similar down-to-earth parents, but many, many parents are not. By “realistic” I do not mean that they do not know their own children. (Of course they do, which is why I really, really want parental input and why I know how valuable it is to the process.)
However, probably more than half of parents fall into the trap of tunnel vision. While they can rattle off the student’s strengths and weaknesses, they are not calculating that profile in the context of that high school, that county, that region, that State, the nation, and the planet. They approach admissions in an “absolute” way, not a comparative way. But today, all college admissions is comparative – yes, even for most publics. The supportive yet more objective and comprehensive viewpoint of a counselor can be enormously beneficial in creating a desirable college list, limiting excesses yet locating where that student might have an edge vs. other “similar” students in his or her class.