No other games have a direct fake money to real money pipeline. The trade system, and its API for external use, make it super easy to run those sites.
They could take the API away, but I doubt that would actually kill the off-site gambling scene if the trade system itself is kept. As long as you can give your items to someone else, they will have ways of extracting real money from people and if they can do so in a way that greatly benefits themselves over the users (as with gambling for the skins), they will continue to do so. But at least Valve wouldn’t be profiting off it, in that case.
No other games have a direct fake money to real money pipeline. The trade system, and its API for external use, make it super easy to run those sites.
They could take the API away, but I doubt that would actually kill the off-site gambling scene if the trade system itself is kept. As long as you can give your items to someone else, they will have ways of extracting real money from people and if they can do so in a way that greatly benefits themselves over the users (as with gambling for the skins), they will continue to do so. But at least Valve wouldn’t be profiting off it, in that case.