I haven't been regularly using Debian in about 15 years now, so I don't know how things are nowadays. But back in the day when I was running Debian unstable on

I haven't been regularly using Debian in about 15 years now, so I don't know how things are nowadays. But back in the day when I was running Debian unstable on my desktop, temporary breakages in dependencies or in individual packages weren't that uncommon. I think sometimes some functionality was broken for a while when there was some kind of a transition going on. Those were entirely understandable given sid's nature, and it was much more reliable and functional than one would have expected from an "unstable" active development OS distro. It wasn't unstable in the sense of crashing or being generally buggy, and it was generally quite possible to use it as an everyday desktop. It did, at least back then, require more active administration and a corresponding mindset than a fire-and-forget stable release would, though. Sid might of course work as a basis for a distro for someone like Valve, but I think they'd need to do something similar to what Ubuntu does with freezes and weeding out issues before releases, or at the least have some kind of a delay before updates were pushed to non-testing devices if they based directly on the unstable release.