they are as long as your hardware works with steamvr
That's the whole point.
They are because they make sure that every hardware works with Steam VR, which they are developing. There is also more too this, you have to actively redesign how controlls work in the game because index, rift and wmr controllers have different options. It would have been so easy for them to lock out people from Steam VR and establish dominance for vive and index. But they didn't. Just like they aren't forcing devs to implement the steam controller. Instead they made sure that every controller works with Steam and can be used and remapped.
Point is: It's an active effort to make sure that everybody with VR can play this. A deliberate choice and not a coincidence because my rift works with Steam VR.
For the it's not on the oculus store argument. So what? I never had a problem with a publisher putting a first party, self funded and self developed title on their own launcher. I'm buying from oculus, from Ubi, from origin, I buy a lot from gog and Steam.
For the fed up with consoles argument.
They also stopped making single player games and now here we are with a new single player Half Life game. Things can change. Even EA can make a triple A, no bullshit single player game and publish it on Steam.