This isolates steam games from the rest of the things running on the machine, which dramatically reduces the number of variables Valve has to consider for suppo

This isolates steam games from the rest of the things running on the machine, which dramatically reduces the number of variables Valve has to consider for supporting a Linux game. This means they can support more games with fewer resources, or give better support to more games. With namespaces and cgroups and chroot and bind mounts you can cobble together an isolated linux distro running on the same kernel as yours. So for example, Steam can target having a game run on Ubuntu 16.04, and ensure that it runs well there, while you can go ahead and use Arch, or Fedora 31 or whatever. It's like virtualization except that it doesn't translate every instruction, it only adds some overhead to certain syscalls.