I'll admit this feature should have definitely been opt-in. But when the update came out there was a big pop-up on your screen when you logged in. Where you just turned all of this off and hit save. It is super easy to disable.
The sharing what I watch with friends part is dumb. But it is pretty cool how you can recommend stuff to friends.
I got the pop up. I disabled it. But I just got an email from Plex telling me everything my family member watched in the last week. This is complete shit!!
It's not perfect, but at least you're only seeing others' activity.
There's hopefully a "discover" email notification you can disable. I haven't been bothered enough to check yet. Worst case, it could be filtered out pretty easily.
I thought I was opting out of my account and my server. But nope, Plex is scraping up everything that's on my server and shipping it in an email to other people including me.
I followed the instructions and opted out yet I'm still seeing what my users watched along with getting emails listing the same. I'm certain none of my users are interested in this and likely skipped through the pop-up without reading/comprehending it.