My Linux system uses about 1 GB idle and yet I’m glad to have 16 GB - not because I wouldn’t mostly be fine with 8, but because it just keeps more doors open. Can run more demanding programs, more programs simultaneously, can host something in the background, …

The OS itself is more efficient than Windows, yes. But that’s not a hard task, and it’s less efficient than many Linux distros. No matter how efficient you are, 8 GB non-expandable RAM is not enough nowadays.