as difficult as plugging in a flash drive
That's a gross over-simplification
They have to
- Download the windows ISO
- How do you find the original ISO and not a cracked one?
- Get instructions to modify the ISO
- Hope you get the right set of instructions from a genuine website
- Download Rufus and install
- Make backup of their data
- Hope you disabled Bitlocker also
- Reboot and press the F? key to change boot order (F? varies from system to system)
- How do you even find the right key for this?
- Follow the installation process
One of the reasons Linux is not widespread is because following these "simple" instructions is too much for an average user. So I doubt a Windows user will be bothered to modify their OS. I have installed different variants of Linux 100s of time and even I need to check online if their are any hidden gotchas.
The Chromium base, which is what Steam is built upon, itself isn't supported on Win 7,8. Can Valve work upon it to make it backwards compatible? Maybe. Will it be a pain in the ass to maintain? Absolutely.
Also, if you don't want to upgrade to Win11, you can make a 2nd partition for Linux and enjoy your games.