If you only have three hours, can't detect fraud, can't tell if the the paper is even real. Then what's the point of even doing the peer review? Again, peer review offered no value at all in this case.

Peer review can still inspect whether the evidence presented in a paper would—if not fabricated—truly be enough to support the paper's conclusion. Mistaken analysis of honestly collected data, improper experimental methods, flawed proofs, etc. can all show up at review time.

You can certainly come to that conclusion if you'd like. Arxiv exists. But "peer review isn't especially usrful" and "these entire fields are nonsense" are very different conclusions.