Is that true on APFS? I know they added it to HFS+ for Time Machine, but I’d assumed it’s no longer necessary (or possible) with the newer filesystem that allows for real snapshots.
It’s no longer possible.
I miss this in the days of APFS actually. As much as it’s potentially dangerous, in a system without bind mounts readily available it really was sometimes the best solution to a problem. Mainly used it to allow various directories that couldn’t be moved to be re-homed, looking at you OneDrive.