If you are talking about the massive 'steam runtime' which forces you (indeed...) to compile the 'user namespace' into you kernel, it is only a shabby/not reliable (and disgusting) way to avoid to have to generate 'correct' ELF64 binaries for broad 'distro' support and long term support. Basically, they ship their own full blown distro userland (yep...), but those who did that are hypocrit and dishonnest (not even of bad faith): they still depends on the user linux kernel and system interface shared libs (for instance userland drivers) which fails to load if not sastifying all the whims of "linux" valve devs: it does happen because GNU symbol version/glibc mistmatches and kernels without the weird features and SPECIFIC/EXACT ELF/file system configuration this valve userland wants). Additionally, and probably the worst: game devs will think they have "linux" support, but actually they only have some shabby and unreliable "valve userland linux _ONLY_" support and not a real and "correct" broad "linux" support: namely they ship for something else than valve, likely their binaries won't load anymore.

This is probably one of the worst "linux" ideas from valve, and by very far. This is basically the definition of accute "enshitification", which could be tainted with abuse of dominant position.

I did show how to do all that honestly and 'correctly' in my previous post. This is basically software development 101 for ELF based platforms...

As I pointed out, the real core of the issue is ELF which we know now is completely obsolete on modern hardware architectures for CPU exes and dynamic libraries and more of a kludge/bloat and issue generator than anything else (like microsoft PE+).