Everyone knows OS and software, browsers, etc all use way more RAM than they used to, and arguably more than they rightfully should. Bloatware, etc.
I saw something recently that alleged MS puts a lot of shit into PCs that say they are doing one thing but are really doing another.
It would be wild if they are basically using the PCs of the world to do something like crunch numbers, mine bitcoin, etc. Oh, hey, this guy has 12 gigs of ram and is only "using" 4, that's 8 for us to sap.
Except, if everyone idles "hot" because everyone uses Windows 10 then everyone will think their hot idling is actually cold idling.
The only way to really test it is compare Windows idling to Linux idling and if your PC components are slightly more utilized under Windows than Linux, it is possible that difference is due to MS doing something for their benefit with your hardware.