Linux as demo dev platform has the issues you mentioned, but as a competition platform it suffers because there is has not been any good baseline/platform to set as a standard. For Windows its easy to define in compo rules that the compo machine is clean Windows X installation with latest patches and drivers as of day Y.
For demos the social aspect is important and one thing Windows is good at is that you have good chance of being able to run random exe you downloaded, which is far less a given with Linux and especially with 3d graphics and audio
Flatpak might now represent the sort of platform that could be good enough, but really the best would be to have something similar but more minimal and specifically designed for demos; I'm thinking some kind of sandbox that would run single elf executable and expose just enough primitives (mesa, wayland, pipewire, glibc) to make democoding feasible and would give fair even ground for sizecoding.
For demos the social aspect is important and one thing Windows is good at is that you have good chance of being able to run random exe you downloaded, which is far less a given with Linux and especially with 3d graphics and audio
Flatpak might now represent the sort of platform that could be good enough, but really the best would be to have something similar but more minimal and specifically designed for demos; I'm thinking some kind of sandbox that would run single elf executable and expose just enough primitives (mesa, wayland, pipewire, glibc) to make democoding feasible and would give fair even ground for sizecoding.