ESP8266 wifi-enabled microcontrollers became known to the western world in 2014. They quickly became a favorite of hobbyists but more importantly, at the heart of many or even most commercial wifi-controlled switches, outlets, light bulbs and other devices, you'll find an ESP8266 (or perhaps its cousin the ESP32). What's not to love that for about 5 bucks you can create a wifi-enabled device using Arduino code?
There is a huge infrastructure developed around these devices for both homemade and commercial devices. The web service IFTTT (If This Then That) allows integration of commercial devices from different manufacturers and homebrew devices. For example, if my homebrew ESP8266 device detects that the temperature is over a certain point, by interfacing to IFTTT, my vent fan controlled by an iTead Sonoff module can be turned on. Thanks to services like IFTTT, you're not constrained to one manufacturer's system.
At home, I don't actually use Alexa. I use Goggle Home as a voice interface. There are about 37 ESP8266s on the network, mostly controlling lights but also able to open the garage doors, controlling soldering irons in my lab, monitoring temperatures around the house, etc. I have one ESP8266 that's setup as an IR remote for my Pioneer amp, after Pioneer abandoned their remote control app so it doesn't work with current versions of Android phones.
I don't have a wifi-enabled hot pot, bbq thermometer or washer, although such devices do exist. If you can add wifi capability for less than 5 bucks, it's not unreasonable to add wifi to a product costing 50 bucks.
A lot of this technology is for convenience. Yes, I rather enjoy making my way to bed as I ask Google to turn on and off lights as I go. It's handy in the kitchen or lab to ask Google to set a timer or ask it to do a conversion or other math. With my soldering irons, it's a convenience and a safety feature. I know with a single voice command that all the heat-producing devices are off, even if I forgot to turn them off using their switches.
How about some other safety features? At my grandmother's house, the front door lock is wifi enabled. Why is this a safety feature? Suppose she needs help but can't get to the door to unlock it? I can remotely unlock it so the fire department doesn't need to break down the door to gain access. In an emergency, precious time could be saved, as well as the expense of repairing the door. And Google is just a shout away to get help in the first place.
There's also a wifi-enabled Bissell Crosswave electric mop at grandmother's. Why does a mop need to be wifi enabled? If the time comes where we have to hire some additional help, there's a web app that allows you to track usage. Did the help really mop or just tell you that they did?
There are some 20-billion ESP8266 modules in use. Sure, it's handy to control the lights, but is it worth the expense? iTead's Sonoff modules start at 5 bucks each. More polished consumer switches can be had for less than 10 bucks. The ESP8266 has enabled this ubiquitous[/i] technology.
So IoT isn't a flop, and as long as Internet is around, I suspect it will be here to stay.