EDIT: To be honest, knowledge of the hash of a block can be used as a proof that something has happened AFTER a particular event (similarly to a picture of a hostage with the newspaper).
But you can't prove that something has happened BEFORE a particular event using Bitcoin hashes.
Also, this "feature" is unrelated to Bitcoin being a cryptocurrency. You can have cryptocurrencies without "global time" (e.g. NANO).
Yes, you can do it if you put the hash of a message INTO the chain as a transaction (I think they do something of this kind). But in this way you will share the limits of the Bitcoin network. They claim they do it in some efficient way, though. But I wouldn't trust it without checking their algorithm.
Anyway, any other "linear" blockchain (e.g. with PoS consensus) can do the same work. No wasting of resources is needed.
But you can't prove that something has happened BEFORE a particular event using Bitcoin hashes.
Also, this "feature" is unrelated to Bitcoin being a cryptocurrency. You can have cryptocurrencies without "global time" (e.g. NANO).