Comment by overfeed

Microsoft's threat was more overt than that: the initial plan was for Microsoft to be the sole signing authority for Windows apps in Windows 7, while simultaneously locking down the OS from pre-boot onwards and not executing unsigned binaries. This would have killed not only Steam games, but Steam itself wouldn't be distributable. Microsoft forced Gabe's hand! Valve had to pivot away from being 100% dependant on Windows as a matter of corporate survival.