The way IoT is described and understood today IS stupid, kind of like the "information superhighway" description in the early 1990s. But there is real, almost infinite potential in pieces of code doing business with other pieces of code (not toasters) and the blockchain is almost ideal for that kind of app.
The basic use case I imagine is the situation where two machines with two different owners are drawing from the same utility, say electric power, being offered by a third party. Suppose there isn't enough to power both of them. How are the machines to decide who gets priority in receiving the power?
Well, if the owner of Machine 1 has a high preference for the machine to run uninterrupted (say a server), even if it were to be expensive, he can pre-allocate some spending money to the machine, as an insurance policy in case of power shortages. Meanwhile, the owner of Machine 2, maybe a poorer person or maybe someone who cares less if their machine's operations were temporarily interrupted (say a clothes dryer), would not do this. In fact, they may even allow their machine to sell excess power if someone is paying enough for it.
Then the person who values the resource more can pay for it, enriching others who value the resource less.
This could be for electricity, for driverless cars negotiating right of way on the road for users of different income classes or different time preferences (rushing to the hospital vs. someone just going shopping), or for any other rivalrous good.
So it's basically a way to make machines more effective agents on the owners' behalf. Whereas before any situation that required a monetary transfer in order to effectuate a mutually beneficial deal would have required the owners to negotiate directly. If the matter is too trifling, it would just be annoying and a waste of time to negotiate. Instead, have your machines do it. They couldn't do this before, not just because they weren't interconnected, but also because they have no way of transferring value to each other.
Bitcoin enables this. And the scale can be extremely small, so that even the slightest possibility of mutually beneficial trade is capitalized on.
IoT by itself enables this to happen within one's own property, like the different appliances in your own house, because no other owners are involved so no money needs to change hands. The dishwasher doesn't mind taking a 5-minute break to give extra power to another appliance that needs it. It needs no monetary compensation, because the owner owns both appliances.
It's when this kind of exchange happens with someone else, especially a total stranger, that it becomes necessary for money to change hands.
Now some people imagine this as heaven for the rich, like if for example a rich driver could flip all the red lights green. How sucky would that be if you had to wait at extra-long reds? But no. You had already preset the amount you were willing to pay in bidding for the traffic light to change, and it was far less...but more importantly you get paid for your waiting time. If it's not worth your while to wait and get paid today, just set your asking price higher (a dial just for this purpose is on your dashboard).
You only wait if the other driver is offering enough to make you interested in waiting.This guarantees that everyone benefits from the deal. If the rich driver ultimately wins out and gets the light flipped, everyone else - by hypothesis - gets at least enough money to make it worth their while. Of course the more crowded the intersection the more the rich driver would have to pay, but some will. Everyone is better off, because goods (in this case road space and right of way) are allocated most efficiently by the
price system.