This is bigger than it sounds for distros. The 32-bit Steam client was the main reason a lot of distros kept full 32-bit library support around. Ubuntu tried to drop i386 back in 2019 and walked it back largely because of Steam.

Older 32-bit games will still need those libraries, so multilib isn't going away tomorrow, but at least the client itself stops being the reason. And running it inside the runtime container should mean fewer "works on Arch, broken on Fedora" kinds of issues.

Honestly surprised this wasn't already a rule. The number of times I've bought something on day one and the first thing I see is a launcher error or a missing DLL is kind of absurd for a store that takes 30%.

The Steam Deck Verified stuff makes it worse, because people trust that badge. If a patch breaks the game on Deck and the badge stays up for weeks, that's on Valve too, not just the dev. Five minutes of a human launching the actual depot would catch most of the dumb ones: wrong launch option, wrong exe, Linux script pointing at nothing.