Have similar frameworks been previously implemented or was this idea first published?
I have not previously seen the framework exactly in the form in which the author of the article wants to create it. There are some platforms, but they are created on only one protocol and are limited in their functionality.
If you mean creating value for internal game points and coins, then I have not seen such platforms too. STONE could attract new gamers and increase the liquidity of some tokens, which would have a positive impact on the entire crypto market.
I think that this platform will be useful primarily for decentralized casinos, as many of them have their own game coins that need the exchange capabilities that the STONE platform can provide.
You are right, I know one decentralized casino that has internal coins, but now they cannot be exchanged for, for example, usdt or other tokens. I think the STONE platform will greatly help many game developers if it is implemented.