If only there was a technology for storing unforgeable timestamps in a way that didn't depend on the honesty and competence of any one person or organization
It would have to have some intrinsic mechanism to encourage people to store and interact with the system though..maybe people could prove they worked on it and then trade it for other things of value?
You can trivially implement this using a timestamp authority (TSA). This can be done without the blockchain, and there are several free publicly available services that do this.