The “dream” is decentralized ownership. If you buy an item in a game, you could resell it to someone else outside the game (in theory this could mean that a game wouldn’t need to create its own marketplace). In theory items could be used across multiple games or platforms.
In reality, game publishers have little incentive to actually do the above things. Why would game x want to support items sold in game y? Why would a platform want to support a secondary market if that would only eat into the primary market.
There are some neat ideas, but the player base is too jaded against it for it to go anywhere anytime soon.