Messaging you requires at best only enough Internet access to send a message. It doesn't require all other functionality to be Internet dependent.
Frankly, the way these IoT devices are designed to be just dumb terminals to some cloud on the other side of the world, it's just bad engineering, in service of anticonsumer business.
Perfect IoT device would include an internal scripting language (ideally standardized and easy to grasp, embedded python/js/lua etc) and API exposing all of gadgets hardware. This way user/owner/external service providers could supply their own script snippets implementing desired functionality. Aka general computing.
Imaging buying "smart light" thats actually smart enough to do what you want it to do.
Frankly, the way these IoT devices are designed to be just dumb terminals to some cloud on the other side of the world, it's just bad engineering, in service of anticonsumer business.