We will want a Decentralised Marketplace because the idea is to create a finacial freedom.
One of the things you might not want is a single merchant controlling and seeing what you buy and what you also may not want.
Having a Decentralised Marketplace would be perfect so that you wouldn't have someone controlling by using ZCoins to buy and sell, or maybe even buying and selling ZCoin itself, without relying on a single website, just in case it gets shut down, and if it does, you will still be able to buy and sell, also an ideal place to build the Znodes that are being planned, allowing Znodes to be an extra layer to provide for the Decentralised Marketplace, that would also mean Znodes wouldn't just be about whatever intrest of what it is generating.
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From @stammy