Indeed, considering that bitcoin is a decentralized peer to peer cryptocurrency, it doesn’t make much sense to create in-games tokens. Game developers could have bitcoin as the in-game token.

Then there wouldn’t be the cost for creating other tokens, need for players to convert them to bitcoin before exiting nor the risk of players’ value being decreased because of over-issue of the tokens.

Having said that, the game developers are better placed to understand the industry. Maybe it is logical to create game’s own tokens.

But your observation makes a lot of sense.