Personally, I think it's a case where, when you have a hammer (like a religion or an overly simplified narrative) everything looks like a nail. It's not novel or academically serious to suggest Micronesian economics were at their best when giant stones represented wealth or that coin clipping was the sole downfall of Rome.
Discussion
I didn't get the impression that he was making that strong of a claim when I read the book. Maybe I need to re-read it. The rai stones were only ideal in the sense that the supply was not easily inflated. He claimed that coin clipping resulted in the destruction of capital from the general population that led to serfdom when it collapsed. I don't think he actually claimed that it was the cause of the downfall, but that if syphoning that amount of wealth had been attempted through oppressive taxation, it would have been more apparent to the average person and would have led to uprising earlier, which if that had created reform, may have prevented it's downfall.