Fair points, but from what i know, those applications you mentioned remains centralized, ended up failure or don't use blockchain (only used as buzzword to raise hype).
IMO those applications can indeed be used decentralized.
The supply chain, for example.
You would be able to track the harvesting of the cottage, the transport via ships, the creation of yarn and finally the manufacturing of a shirt completely transparent.
There are multiple entities involved in such a process. And with a blockchain tracking all of these steps, there would basically be no central authority.
Yet, there is not a single project which does that.
Anything one can find at the moment, indeed just uses blockchain as a buzzword. But i am confident that we can have several applications backed by a blockchain in the future which have absolutely nothing to do with cryptocurrencies.
supply chains, are better off using permissioned chains with fewer nodes. there is no need for such huge decentralization. this also allows there to be no transaction fees which is vital. 3- 5 nodes is quite enough for a supply chain blockchain.
private chain
no fees
just spin up 3 nodes on AWS.
1 controlled by devs
2 controlled by farmers association
3 controlled by distributor
maybe another one controlled by retailer.
then periodically write the state on ethereum or BTC blockchain for notarisation
there it is.