No, I think you should write more about it. Motivations, what about programs or scripts that require writing or at least modifying files in $HOME, etc.? You say

No, I think you should write more about it. Motivations, what about programs or scripts that require writing or at least modifying files in $HOME, etc.? You say it is rare, but is it really? Also what is your way when you want to communicate between two programs? What is your preferred method of IPC? I will check how much my system works if I do the same thing as you, on Linux. :D FWIW I use firejail so applications cannot run anything in $HOME and temporarily (heh) mounted tmpfs (two separate options).