Exactly this, but my thinking was that it might have some value to the publisher to build a marketplace around the content.
As an example - games like Fortnite, Warzone and Apex Legends rely on loot as the sole driver of revenue. Having in-game rare items freely tradable akin to the trading card concept that NFTs are constantly compared to could have value in itself.
If I’m a real fan of one of those games and I stumble upon a diamond-encrusted level 100 golden sniper rifle (sorry I’ve no idea what a good example of a rare item is in one of those games), then the money someone may pay for that is (e.g.) $1k.
Giving me the ability to sell that on to someone could not only drive publicity for the game (EVE online made world news years ago because of the real monetary value lost in their battles) but encourage me to play that game over rivals as there’s perceptible real-world value for my invested time and effort.
The downside I was thinking of above is that the publisher may not want to enable that for a bunch of reasons - the suggestion above sounds like a good way to resolve their revenue on the transactions, but the status quo of the items being non-transferable may be preferable as they’ll overall sell more loot directly to individual customers under the current system.