The problem that proof-of-work blockchain solves is widely misunderstood. It uses proof-of-work to establish consensus over points in time which are universally unique. Prior to the publication of Satoshi's paper we did not have a solution to this problem and for that reason it is a significant advance in technology. I wouldn't call it crappy, it's actually quite brilliant. For a detailed description see this: https:…
http://satoshi.nakamotoinstitute.org/emails/cryptography/11/
The magical thing is that you can actually know that the distributed system is consistent by how much work was performed.