One of the services listed is Screen Time. Maybe I'm mistaken but isn't that the feature on iPhones where you can see how much time you spend in each app? Why would that require Apple's servers.
My guess is that it's a glorified analytics system for Apple which they retooled into a useful service for end users.
Edit: actually screen time is the feature that measures how long you’re spending on each device each week. I’m not sure why that needs to talk to the cloud unless devs also get the inverse metrics.