It blows me away when I play a game like Valheim or Vampire Survivor and find out the game that took 1000 hours of my life is smaller than a two hour movie.
When I built a new PC last year, I was wondering how I managed to filled up a 4TB NVME in only 6 months... until I downloaded one of those programs that breaks down your hard drive usage.
Games, it's all games. I don't even consider myself a gamer. I can't even begin to imagine the struggle of an actual gamer who is still stuck with a 256GB SATA SSD as their only high speed drive. What do you do when nearly every game that comes out these days is 100GB+ and requires an SSD?
Also the system files aren't really the most important files. While it's a pain in the ass, you can reinstall your OS and get that all back again.
Reinstalling all of your games is going to take more time, and if you lost a save file, well you're never getting that back. Personal photos, videos, etc. are even a bigger priority.
So I tend to to think of the drive /home is mounted on to be the "primary drive" as it's the most important. The root is just the system files, needed for the OS, but not nearly as important as /home.