Hi, author here: whether it's a valid use case depends on your level of OCD, but the difference compared to symlinks or bind mounts is that you will have a clean home: e.g. `ls -la` won't show any "hidden" files.
Also, completely unrelated to my motivation, someone pointed out that modetc could be used to quickly hotfix packages built with Nix.
Say that you need to fix a CVE in openssl, normally that would require to rebuild all dependent packages, which takes a long time. Instead with something like modetc you could build just openssl and rewrite /nix/store/<hash>-openssl-3.6.0/ -> /nix/store/<hash>-openssl-3.6.0-hotfix/.
Another application might be replacing some configuration file with placeholders for secrets, with one file with the secrets substituted in, without having to modify it in place, possibly only for a specific UID. This is something you might find useful on NixOS.
If I symlink ~/.ssh -> ~/.config/ssh, I still have .ssh in my ~. Whereas if I rewrite it, I don't.
Will you not have `~/.ssh`? If you have `.ssh .config/ssh` as a rewrite rule, `stat ~/.ssh` will still find it.
The point is to have a clean home directory.
Abandon hope.
I just treat ~ as a system-owned configuration area, and put my actual files (documents, photos, etc.) in a completely different hierarchy under /.
I have been doing this for decades. My files are in a sub-directory of $HOME. It also makes it very obvious when a piece of software does not treat your $HOME with respect.
On Windows this was always easier because, for some reason, most everyone respected %appdata% compared to XDG_CONFIG_HOME, but also because hidden files wasn’t just a naming convention but an actual separate metadata flag.
You could write a kernel module, then, that just hides certain symlinks from you (which is effectively what this module is).
That ship has sailed 30 years ago.
The use case is that you can actually use your home directory without either (a) hiding files or (b) wading through 40 config files and dirs that XDG ignorant devs put there.