Making something like 3dsen is a much more difficult task than being able to display a game that is using a 3d engine and so would generally be fundamentally capable of providing a stereoscopic view. That said, most of them currently don’t offer it anyway and it’s still not quite zero effort to add such a capability.

It does seem like Valve are saying they want to let you view a game in a stereoscopic 3D if the game has support for it built-in already so it would be 3d support for flat games (meaning games primarily made to be run on a screen) but only if the game has support for it. That’s good but does mean there’s still a need for either developers or 3rd parties to make the changes needed for it to function.

FWIW, I didn’t get it at first but found it funny after reading the comment where you explained it.

This would be a dream feature for me as even many flat games become so much more visually impressive and immersive experiences when you are able to look at them in real 3D. Currently you can get a decent number of games displayed this way if you have a stereoscopy-capable device but it’s just a royal PITA that involves lots of fiddling with config so having that be easy on very comfortable hardware like the Frame would be game-changing as far as I am concerned.