I don't think anyone has made the claim that it was "crazy" to have found plates with religious writing on them.

The only criticism relating even remotely to that would be that there was no physical evidence presented for the existence of the Golden plates presumably found by Joseph Smith and that the sources presented for the existence and historicity of the Golden plates are either dubious (from conflictions or flat out disproof of accounts by witnesses or others) or have no sources outside of Mormon faith to prove their authenticity.

That religious texts have been written down in previous civilizations and used to document religious codes, law and/or beliefs does not mean the Golden plates are any more authentic than they currently are.