Stretch isn't just a "parents" app or a leaders app. It's a family app. We allow family leaders who are parents or legal guardians to create accounts for users under 13 years old--for example, the founders kids use Stretch all the time.
The family leader (a specific role in Stretch) can create other (family) members and caregivers. There can be multiple family leaders. Users under 13 cannot be a family leader. (You can lie about your kids' ages but it's not particularly helpful to them.) But these users control their own accounts and cannot create other users. They have full rights to create new content and view whatever content they have permission to see.