> Real-estate on the Moon is also divisible and un-manufacturable, but no-one seems to be arguing that we should base a monetary system on _that_.
From the perspective of a fiat currency serving as a store of value, Moon real estate is a great idea. The exact amount and location of it is available to anyone in the world; it's tamper-proof; and unlike regular paper money, it's difficult for it to be inflated.
A currency with zero nominal inflation translates to effective deflation in a growing economy. If you own x% of the moon, and no more moon can be printed, you'll hold your lunar notes under a mattress waiting for their value to rise and nothing productive will ever get financing.
From the perspective of a fiat currency serving as a store of value, Moon real estate is a great idea. The exact amount and location of it is available to anyone in the world; it's tamper-proof; and unlike regular paper money, it's difficult for it to be inflated.