The solution critically needs to be independent of the internet.
This is why:
There are over 7 billion people upon earth.
Just over 2,4 billion have internet.
Of that 2,4 billion, about a third have broadband access.
Way less than a billion have reliable, uninterrupted services at affordable prices.
Cloud-based computing in general is therefore not widespread.
Apple has a small global footprint yet a fair share of its user base are located in regions without practical broadband connectiviity. We bought Apple for its local sync, especially via tethering.
In global terms, iCloud users are by far a minority. If you live away from the USA, you soon realise how fragile and compromised the Intetnet is. Natural disasters, power outages, accidents and even terrorism/sabotage can and do interrupt connectivity. This post will travel 23,140km via a detoured undersea cable so that it can be saved on Apple's servers. It goes from the tip of Africa along the west coast up to the UK and from there across the Atlantic to the USA. The cables get severed and on our harbour there are two ships that have the immense task of maintaining these cables.
My USB cable is two feet long and works better and is not exposed to risk.
Until broadband works in practice across the globe, we cannot rely upon internet connectivity. Its is only good for email and browsing, not for handling copious amounts of data. Unless you are, of course, located where broadband actually works on practice.