They could have gone Unix and not contributed upstream like PlayStation did.
Oculus was a device. Valve built SteamVR literally for the Rift (I had the original developer model and using Steam was pretty much essential). Valve also ensured that SteamVR supported other devices too when they came to market, levelling the playing field and enabling consumers to pick and choose hardware without having to buy games across multiple different marketplaces.
Valve pay their employees what they’re worth and share their success with them rather than devaluing them and extracting value from them. That’s pretty good going. And given how much they do with so few, it says a lot about their culture and ethic.
I don’t know about other gamers but I dislike EGS because it’s simply an inferior product and I vote with my wallet. If they offer me more value than a competitor, I’ll gladly use them. I use GOG, itch.io, and Xbox GamePass so it’s not like I’m averse to other platforms. I just don’t see why, if a game is on EGS and Steam (and not on GamePass), what value is there to me as a consumer with going with EGS?