Please refer to bug#14444 for the background here.

Trying to mount to a mount point which is a symlink gives (in journalctl):

Jul 13 10:21:55 ftglap systemd[1]: home-ftg-.thunderbird.mount: Mount on symlink
/home/ftg/.thunderbird not allowed.
Jul 13 10:21:55 ftglap systemd[1]: home-ftg-.thunderbird.mount: Failed to run 'm
ount' task: Too many levels of symbolic links
Jul 13 10:21:55 ftglap systemd[1]: Failed to mount /home/ftg/.thunderbird.
Jul 13 10:21:55 ftglap systemd[1]: Dependency failed for Remote File Systems.
Jul 13 10:21:55 ftglap systemd[1]: remote-fs.target: Job remote-fs.target/start
failed with result 'dependency'.
Jul 13 10:21:55 ftglap systemd[1]: home-ftg-.thunderbird.mount: Unit entered fai
led state.

However, as seen in bug#14444, a follow-up "mount -t nfs -a" successfully mounts on the symlink without complaint.

Here, /home/ftg/.thunderbird is a symlink to /data/ftg/.thunderbird.  If I change the mount point to /data/ftg/.thunderbird, I get:

Jul 13 11:25:51 ftglap systemd[1]: data-ftg-.thunderbird.mount: Directory /data/ftg/.thunderbird to mount over is not empty, mounting anyway.

This is an improvement, as systemd used to refuse to do the mount here as well.

Why is systemd complaining about stuff that mount handles without complaint ?

Reproducible: 

Steps to Reproduce: