The answer to your question why is because I arbitrarily decided on that years ago. That's basically all there is to it.
The answer to your file ownership problems I can't answer, because I don't have that happening. My files are mounted like so:
LABEL=BigHD /mnt/BigHD btrfs nosuid,nodev,nofail,noatime,x-gvfs-show,compress-force=zstd:1 0 0
Dude that’s just way too on the nose. Please don’t agitate against your betters. They have money and are therefore better than you, don’t you know?
I’ve never seen the western propaganda machine be so obvious about it