Developers didn't onboard because it was Vulkan-only. You can release for GOG as an afterthought, but you had to build for Stadia as Another Separate Platform,

Developers didn't onboard because it was Vulkan-only. You can release for GOG as an afterthought, but you had to build for Stadia as Another Separate Platform, and they somehow managed to make their SDK requirements more onerous than Xbox's. They might still of joined if there were any customers, but customers didn't join because of the prospect of needing to buy their existing games again, then pay for a subscription service to play them, on top of the already-not-so-big group of people with great internet but not so great hardware. Though they might of still joined if there were any games. The primary thing Google got wrong was assuming everyone would flock to their service in droves for the promise of the other side of the service, thus forming it. They didn't anticipate that all the roadblocks they installed from the start would prevent any kind of flocking. HN posters will talk about Google's graveyard, but it is not a factor for businesses; Google's history of shuttering perfectly good services doesn't extend to services you actually fork over cash for. And this won't affect that, as it was nowhere near a perfectly good service and was doomed before it was released.