POLIUM ONE

You'd have to define what you mean by "works", since there's a number of separate angles by which the hypothetical breaks down in practice. At the very least, if everything else worked as described at face value then existing PTE games show that they operate much closer to MMO economics than any real-world financial mechanism, and thus don't remain feasible for very long before becoming completely valueless.

Instead you slave on the internet with the Blockchain

Worst part is that there will be core dependencies that force you to play specific trash games like match-3's for exclusive materials, or the overall ecosystem with have a meta form that forces you into specific games for specific materials, such as having to play trash match-3's for the sake of efficiency. Botters would also love to have the ability to be able to have so many options available to them. As soon as one game starts cracking down, move to the next one, always have new games available to dump off your goods. Also it would take having all these games coordinate so that their material values are level across all platforms. If those obsidian were to become worthless in an update for one game, everyone would just unload onto the others for quick cash outs. You'd see volatility everywhere at all times in markets. Not to mention that it'd take one duplication exploit in a buggy game to kill completely unrelated games.