With no opinion on whether this is a good thing or not, the blockchain as described by the original author(s) does allow (as long as the hash function holds up

With no opinion on whether this is a good thing or not, the blockchain as described by the original author(s) does allow (as long as the hash function holds up and there's financial incentive to crunch the numbers) proof of public delivery of a message, thus negating the need for notaries.