How easy is it to know what works when the network is down before purchasing? Do you expect everyone to take down their wifi after purchase to test and return if it doesn't work?
Maybe there should be a mandatory information sheet such as listing all functionality that stops working without a network connection.
Consumer protection regulation with mandatory labeling would be a good answer but, at least in the US, we're not going to have anything like that anytime soon (if ever).
I don't have the enthusiasm to start a competing company. It sounds like the barrier to entry to the market is fairly low, the tech isn't unproven, and there appears to be a ton of margin.
Maybe there should be a mandatory information sheet such as listing all functionality that stops working without a network connection.