The ownership of assets and being able to do what one wants with it is the biggest draw of web3 in gaming. The Steam market is already a big example, and it just being limited to its own ecosystem is the only downside. For games that don't encourage trading/buying/selling of items, the accounts themselves are the ones that are being bought/sold. When games go to web3, all these will be solved, and more freedom will be given to owners. For the developers, they can just put a small fee for every transaction so they can keep earning from these. It is a win-win for everyone.