All true but they’re probably looking to change the paradigm. Maybe (just speculating) people will write simple python apps for IoT applications. I don’t think you could do this sans an OS. What you say is true historically but it doesn’t mean it has to be true in the future.
Don’t get me wrong, I think that IofT is a cool concept. What I was driving at is that most of the uC’s in use today just don’t have the horsepower to handle a TCP/IP stack AND perform the low level functions that a uC are designed for, if you threw in a OS. Use a Atmel AVR as an example. Could you cram all of that into 32kb of memory? You could do it with serial on a commodore or apple IIe (that makes me feel old just typing that).
The Arduino “shield” approach would work best I think. A uC to handle comm protocols, a uC to handle machine function, and serial eeprom to hold the OS, distributed processing. A trip through the manufacturers catalogs should reveal some nice gems to exploit. I think that after years of “wintel” software bloat, the newest crop of programmers are rediscovering the concept of “code efficiency”.