Thanks a lot for the feedback! We're really glad you liked it!
We thought about the MetaFab integration a lot and decided that we would follow the following part of the rules:
"More specifically, for this jam, some ways you can use MetaFab include...
Player account creation, management, and save state..."
We also added an item that's minted to your wallet once you beat the game, so overall the Almanac is some kind of inventory. If we wanted another saving and "inventory" system, we would have to reimplement a different one entirely.
The genre of our game would be some kind of rougelike, and in rougelike games there often isn't much economy going around, so we decided not to force it and use MetaFab for the system we actually needed. Our current inventory system mostly serves as a proof of concept and could be (and probably will be, after the jam) expanded.
Once again, I get where you're coming from, but I think MetaFab is amazing because of the fact that it can solve variety of problems, and be useful to any type of game there is.
I hope this makes sense! Thanks again :)