Blockchain
There may well be fascinating ways one can use blockchain for archives of this sort, but the grandparent comment was essentially useless noise.
Anyway the comment was probably downvoted because it consisted of a single buzzword.
In terms of making sure the work that is done is useful it's fairly hard to do that because if you let someone dictate what work should be done then you potentially allow them to do the work upfront and a 51% attack becomes pretty easy.
I do wonder if there are potential consensus algorithms that rely upon game theory, the threat of being booted off the network, and the need for some investment before they're "trusted" by other peers. The basic idea is that yes, you could 51%-attack the network with a lot less than 51% computing power, but it would never be profitable because if you're discovered you're booted off into your own little partition where nobody plays with you, and the value you get from being part of the network in the future is greater than the value you would get from rewriting history into something only you believe.
51% attacks are possible now - roughly 75% of Bitcoin hashing power is located in China, so if the Chinese government decides that they want to shut it down, they send the military after the largest Bitcoin miners, say "Hash these transactions or else", and take control of the chain. They haven't found it profitable to do so yet, though - what would they gain from it?