The issue of radio spectrum is glossed over in a short bullet-point summary at the end of the article while I believe it deserves to be the article's thesis. The limitations imposed by the radio spectrum and its availability are at the root of every other point made by the author.

You just can't have high bandwidth, excellent protection from interference, and low energy usage all at once. The blcoks of spectrum that offer the best balance of those qualities are already booked up for things like OTA TV broadcasts and "high-cost and high-powered cellular" networks. The issues with mesh networking are also immediately apparent if some classes of device are to be kept on separate networks or have to forgo their role as a node due to the power requirements of a repeater.

A simple example for what airwaves would look like in the crowded "IoT' future is your average apartment complex and the 2.4ghz spectrum. 30+ routers competing for the same tiny space absolutely destroys the quality (latency, throughput, power draw from the devices radio) of the connection. The space is so crowded that you may only see 5-10 networks as the signal from a router 2 stories up is so dirty that you can't even receive the SSID but the interference is still there.

There is only so much spectrum available for use, even if it was all unrestricted. There won't be a mass adoption of networked "things" until someone is able to find a loophole in the laws of physics.