It seems to be just a document describing the protocol of Filecoin, which is fine. The problem is that all these "whitepapers" coming from these cryptocurrency communities seem to be promoted as scientific papers, but in reality do not stand a chance in any science/academic-related setting.
I'd wish they'd give more attention towards the science, if there's any. Otherwise, hey, sure it's just a PDF on some site - but don't call them "papers".