Article says if you added "friends" to share what you're watching, those are the only ones who get the email about what their "friends" are watching...
And it just reports content on your Plex that's registered on IMDB...
Like, it's not plex spying on your search history and reporting what pron you like to your friends.
If you have porn on your plex:
Why?
Maybe don't sign up "friends" so they can see what you're watching...
I read the thread. If you shared a movie with a person before the concept of "Plex friends" existed and they are now considered your Plex friend, no opt in needed.
Even libraries have options to be shared, if it's recommending from non shared libraries that's real fucked up and sounds like a bug and not intentional