For some youth players I believe playing on multiple teams, including high school, during the year provides opportunities for development not realized by playing just club. I have a daughter who plays as a starter for a premier team where she plays exclusively as an outside defender. She looks forward to high school soccer where she plays midfield and forward. She says high school helps her develop attacking skills that help her as a defender in club. While high school doesn't offer the same overall level of team competition she gets in club, she usually matches up against other top club players on the high school fields. She says it puts pressure on her foot skills. While I know she wouldn't be the player she is without her club experience, I believe the opportunity to play multiple positions as a member of club, high school and ODP teams has helped her development overall.
And... most of the D1 inquiries she has received so far are based on an interest in her play at midfield/forward in high school rather than as a defender in club.