To address other points, Microsoft has used Xbox as a trojan house into console gaming, using its PC gaming development to subsidize Xbox development as Sony used its hardware division to subsidize PlayStation development.
The strategic deployment of Xbox on the PC is probably the largest strategic threat to Valve and Steam, which is why Valve developed a way to play Steam games on a self controlled OS.
To address other points, Microsoft has used Xbox as a trojan house into console gaming, using its PC gaming development to subsidize Xbox development as Sony used its hardware division to subsidize PlayStation development.
The strategic deployment of Xbox on the PC is probably the largest strategic threat to Valve and Steam, which is why Valve developed a way to play Steam games on a self controlled OS.