The writer of this article declares that IoT stands for “Interference of Things.” Anything else you may have heard is just marketing hype.
Relatively few connected gadgets will use wireline communications, the bulk of these devices will connect wirelessly over Bluetooth, Wi-Fi, cellular or something else. Some IoT devices will be designed to limit EMI emissions to the proper channels and reject out-of-band power, but many won’t.
Price, power, and size pressures will cause some companies to sell products that work just well enough to pass minimum requirements, if that. There are many connected devices that undergo only self-certification, some of those products would likely fail compliance tests on out of band noise. Also cheap heterodyne receivers are more are more likely to succumb to interference (from other devices or jammers) than more expensive designs.