Recently WhatsApp had to roll back an initiative to share data with her parent company Facebook. This is after receiving a severe backlash from users, which led them to switch to alternative messaging services like Signal and Telegram. The perception of the data sharing between Whatsapp and Facebook is that if two persons are messaging each other about cars on Whatsapp, both of them will start seeing personalised ads for cars on Facebook. It might not be like this in reality, but that’s the perception and hence people are pissed off about the perceived privacy intrusions by these MNC.
I think when communicating with people, we are also collecting personal data. Inside our minds, we have a little secret dossier about the things we know about that person. His likes, dislikes, personality quirks, birthday etc. And from this collection of data, we form an idealised form of what the person is like in our minds.