Parents just have to make sure the kid understands to not cheat before sharing the account. It might sound new to us because we never grew up with this scenario, but it seems reasonable to me.
Again, it's just making sure the kid is a safe driver before letting them borrow keys to the family van.
If the ban worries you, you can just not share the games - this is strictly an upside and there's no penalty for maintaining the status quo and not using this feature.