[babypuncher]

I don't think users take much issue with services collecting data that they feed directly into the system. I find it hard to believe anyone would not expect Facebook to be aware of what their users are doing within Facebook's walls. Personally, I'm very aware of this, and keep this in mind when choosing what data I feed any given service.

The issue has always been that Facebook is tracking you on non-Facebook websites and apps, even if you don't have a Facebook account. From a user's perspective, they never told Facebook what products they were looking at on Etsy, so Facebook collecting that data feels like a violation of their privacy. Things like GDPR and Apple's new IDFA policy do neuter this considerably.