That's because utopian societies fail to account for greed as the normal condition of human beings.  

People are greedy little monkeys who will fling poo at anyone who tries to take our bananas.

Crown Holders, have one way to make money, this is by owning a treasury right and using it to mint.  
If they want to mint more than their allotment, they need to buy more crowns, and this gives them a bigger slice of the economy.

Having crowns means you get a say in how much money in total is being printed, but your share is directly related to how many crowns you own.

If the crown holders print more money than current market prices support then the supply contracts to keep the price stable. 

This means that the system begins to eat into their current balances via negative minting.  Remember it's crown holders, not mints that are on the hook for negative minted amounts.

They need to slow down the printing press for a bit and let the market catch it's breath or pull some of their coins off market, or even buy some on the open market.

If they fail to print enough money, then they lose out on literally having free money.  They're leaving money on the table.

This causes a seesaw or if you prefer an orbit effect where the price trades in a tight range.

It's powered by greed but we all get richer when they are being greedy since their greed is what maintains the balance between supply & demand.