Ah, I didn't know that SteamVR could run without Steam. Can Alyx (once installed) ?
Still, this leaves the issue is that being theoretically Steam-free isn't enough, as the experience with AOSP/Google Play Store has shown.
Valve might be 'pretty good' with their own users, but still the result of Steam's dominance is that it's getting harder and harder to get mods and play multiplayer outside of Steam.