I don't remember who first said it but blockchain has exactly one killer feature, Bitcoin. If you try to adapt it anywhere else you're probably abusing the tech.
The use case is, I can tell when Fedex or the local pizza place is lying to me about my delivery being 30 minutes away, or half a mile down the street, or whether the delivery driver actually attempted to physically deliver my package to my door at 5:47pm or not. (Or Ikea can verify that their subcontracted delivery driver actually got the couch to the buyer on Sunday, or both Uber and I can know exactly where I was dropped off and picked up and when, etc., etc., without either party being able to lie about it.)
A friend of mine agreed that the idea was good, but looked into their implementation and said it was a horrorshow.
Not sure how it worked, though. :(
So zero killer features, then.