Which is exactly the point I still try to get my head around when it comes to supply chains.

First, for blockchain to work you need trustable sources. Problem is, when the aource is trustworthy, what added benefit comes from a blockchain?

Second, having a, theoretically uninterrupted blockchain from the first raw material to, say, a car would provide way to much insight into supply chains. I pretty sure companies do not want that.

Finally, and that is IMHO the haedest point to practically solve, you need to make 100 percent sure that the physical and information flow in your supply chain are never ever seperated. One single separation and your whole blockchain is worthless. And that risk is so incredibly high in the real world it's almost laughable. So, to make sure a given blockchain matches the physical product you need a trustworthy party to assure that. And then, what value does blockchain add?

Someday someone a lot smarter than me will find a use case. At which I will say how damn obvious it is.