Ancient-Red-Dragon: I don't think your OP has done anything actually to prove the premise of that statement.
I'm sure Valve loves Windows just fine.
timppu: At least in the past Valve/Gabe has demonstrated their nervousness over where Windows has been heading:
https://arstechnica.com/gaming/2012/07/steams-newell-windows-8-catastrophe-driving-valve-to-embrace-linux/
Steam Deck running Linux, instead of Windows like pretty much all the other PC gaming handhelds, kinda shows that apparently hasn't changed at Valve. Linux is their plan B.
Head of Epic has shown similar sentiments, but they haven't done much of anything to embrace any alternatives on their store.
Breja: Then how will they fit in our pockets?
timppu: Bigger pockets. Problem solved.
Both Gabe's and Tim's fear of Windows 8 came from a totally imaginary threat.
With Win 8 Microsoft did 3 things
1st) Built a Digital Store into the OS
2nd) Created a whole new application Environment with UWP
3rd) Made a version of windows that only used UWP
Influential People who all should have known better, put 2 and 2 together and made fish.
The belief was Microsoft was about to copy Apple and create a walled garden OS where all apps and transactions must go through them.
Now anyone with even the most cursory knowledge of Microsofts core business (its not PC gamers or people at home surfing the interwebs) would know that simply could never happen. It would destroy an ecosystem they spent decades growing.
Also anyone that has a vague idea what the phrase "Anti-trust" means, also knows Microsoft could not do this, well not with out being sued al the way back to Win 3.11 for Workgroups.