1)
For starters, a SteamOS\Linux Exclusive? You might as well just make the damn thing a Stadia Exclusive because no one is going to be jumping on that until its on other platforms.
2) Secondly, you want to talk shit on Epic because god forbid you have to install another game client, but somehow that is worse than installing/using a whole other Operating System in comparison to a single app launcher? What the hell is the formation in logic is that?
3) Finally, anything that Valve would put their force in with their original IP's would be more than enough to get people flocking over to their hardware. Hell it did enough to get VR into something more than a fleeting gimmick with the combination Boneworks and HL: Alyx proving that VR games can actually be decent.
4) Also another tidbit, Any Studio Valve has acquired or worked with has only met with failure/closure of said studio, said studio being spit out on its own again, or was cancelled. Valve does not fit well doing things with others, especially in the long term. Valve would have no idea what to do with a studio like Platinum, especially since the types of games they make are radically different from each other.