steam is not a drm-free platform like GOG or Epic Games (some epic games games have additional drm, but most are completely drm-free and there's no client-level drm at all like in steam*).
Most games use the Steam API to check stuff, so Steam client needs to be running.
(I'm actually kinda ok with steam's drm btw, it's not as intrusive as on some other stuff)
I’m fine with the DRM. But why does the window need to open and take several seconds to “connect to the friends network” for a singleplayer game? This doesn’t need to be a blocking process.
Isnt this possible? I do it with blender. Just right click the icon of the game and pin it to your taskbar then click it when you wanna launch the game