Hi Nanobug,
Glad you posted this in here. Yes, the original command only hardlinks directory contents, it won't hardlink the whole directory unfortunately.
Since my earlier post I found and use this command as an easier way to get around this and hardlink entire directories to my PLEX folder.
Sure, Sonarr / Radarr does this in the background, but:
a) I haven't used either (yet)
b) I have a lot of content already downloaded "manually" over the years, which I assume Sonarr and Radarr won't automatically & retroactively detect and hardlink by itself
c) I find this extremely useful for both my PLEX folders and for other applications, such as cross-seeding of torrents on different trackers where the files or folder structures have been altered.