If I was talking to a group of friends in real life, and I realized someone in the group was developing an obsession and closely keeping track of everything I said and subjecting it to endless scrutiny, I would be super creeped out. Even though they had every legal right to do that.
I understand that to some extent my friends build a profile of me in their heads and use it to anticipate like, if I want to go to an event with them. But that's not really a difference of degree, there's a phase change when it becomes an obsession and it becomes a difference of kind.
Similarly sometimes retail workers get to know my taste and will point out some item I would be interested in. Sometimes that makes me uncomfortable, but because I'm shy, not because they did anything wrong. If I learned they were reading my social media profile, it would start feeling uncomfortably close to the plot of The Menu.