What does Post-Monetarism Mean?

[Cray]

I'm just gonna put here (sorry if it's been mentioned already) that a gift economy need not be post-monetary.

I stumbled over an interesting historical example of a society moving to a post-monetary one:
https://en.wikipedia.org/wiki/Heian_period#Economics

The Heinan-era Japanese had partly monetized rice, tying social rank of nobles to the amount of rice their fiefs generated. Rice became a primary medium of exchange and partly displaced currency, but rice was a poor medium of exchange for anyone other than farmers and nobles who could command wagon-load deliveries of the stuff. Payments were often handled by gifts for lack of useful currency.

The situation reminded me of a science fiction novel written in the 2000s [edit] Donald Moffit's Jovian! [/edit] took me forever to remember that...

Anyway, Jovian is about a young gas miner on Jupiter who eventually travels to Venus and Earth and witnesses how the solar system is ruled from (Liechtenstein? Luxembourg?) by corporate-noble families who have gotten out of touch with the impact of their enormous wealth. For example, a noble is willing to disrupt an enormous calcium shipment from Mercury to the Venus terraforming project to assassinate the main character over trivial, petulant motives. Nobles on Earth attempt to one-up each other by resurrecting mammoths and dinosaurs, and work on a near-gifting economy because (like the Heinan) currency was too abstract to them.