I briefly touched on this but steam runtimes (aka shared library runtimes) in practice aren't as isolated as one would assume, an update to glibc is often enough to break applications targeting them. Furthermore, in practice many maintainers think little of video games and are often comfortable breaking them if it helps with the server side of things.

For evidence of this, look no further than Ubuntu, the basis of the steam runtime, dropping 32bit support and breaking all software (video games) that depend on it. Sure you can still use it for older stuff, but there is no future here.