It was specifically the release of Windows RT (Windows 8 on ARM) in 2012 that had people nervous that Microsoft wanted to lock Windows down long-term in the manner of iOS and Apple. Windows RT only ran code signed by Microsoft and only installed programs from Microsoft's store. It failed, and Microsoft let off the gas locking down Windows, but that moment was probably the specific impetus for Gabe Newell to set Valve on a decade long course of building support for Steam and the games in its storefront on Linux. Windows being locked down to the degree of iOS was an existential risk to Valve as a company and Steam as a platform in 2012. It isn't anymore.
Windows RT also drew ire from people other than Newell at the time IIRC. It was widely perceived as a trial balloon for closing down Windows almost completely. The first Steam Machines a decade ago were Valve's answering trial balloon. Both failed, but Valve learned and Microsoft largely did not... They haven't locked down Windows 11 to the point of Windows RT, but they're abusing their users to the point of potentially sabotaging their own market dominance for consumer PCs.
Yes. We could have had Windows on Arm ten years previously, but Microsoft tried to use the platform transition as an opportunity for lock in. Fortunately this meant there were no apps and basically zero take up of WinRT.
This was also closely related to their initial plans with the Xbox One to essentially kill used games, which they were about a decade to fast on rolling out.