As you may know (or not), Steam to this day uses the libraries from Ubuntu 12.04, released in 2012 and are not even updated at all, which causes a large difference in terms of performance. Forcing you to manualy create your own executable with STEAM_RUNTIME=0 to force Steam to use libraries from your system. Some Linux distributions such as ArchLinux has a package specifically made for this situation, but not all distros have that, especially when you require a 32 bit library to run Steam in Native mode in a 1st place.
Then Solus came in and made a decision to use snaps to provide Steam for every single Linux distribution with the option to use it's own native library, even on distros that don't support multilib!
Why You Do This??
It's time to relieve the pressure on distributions for supporting gaming, by doing so through a single point of entry. A snapped LSI will ensure that the Steam/LSI combo would work identically on every distribution, *even if they don't support multilib*. It also ensures we can provide a "perfect" runtime, but ensure its up to date, optimised, and configured explicitly to support LSI & Steam.
TLDR: Single Steam/LSI image that takes all of the Solus gaming/Steam work, and provides it for everyone, on any distro.
Think of it as Steam runtime (default)....but on steroids!
EDIT: Oh great, the forum removes the from the beginning at Solus in the url resulting in a page error.