On Facebook most of the value comes because of the demographic profiling thanks to MAC address, router MAC address (for each wifi you log in too)... basically location. 

Why do you think Facebook’s more recent free WiFi feature requires 24/7 location. 

Then combine location with interests. That leads to the following possible situation (also keeping in mind that Facebook has admitted it buys data from other offline profilers like Nielsen):
A user has liked cruise ship pages. 
* User lives in an affluent location -> is shown $5k for 2 weeks cruise ship holiday
* user lives in a less affluent location/country -> is shown ads to work on a cruise ship. 

Of course it isn’t just area. The ability to track wherever you go is $$$. 

Combined with years of data and likes that is a treasure. 

But even on steem you can notice basic availability of such: upvotes checked against tags. Combined with time spent on each tag. 

Right now there isn’t a Steem app yet tracking location or doing device fingerprinting. But who says that is meant to stay?

Who says no Steem dApp will integrate Facebook’s Pixel to monitor conversion from ad campaigns on Facebook. 

Important to remember: the basic raw data is available to anybody. You can use SteemSQL for a fee or you can just spin up your node and mine it all yourself. Upvotes, transfers, user interaction (through upvotes, comments, and even transfers). Also what dApp each user uses and how often they post to that dApp. It’s all in the blockchain and available to anybody. 

But you’re right, the dataset isn’t as rich as all sneaky tricks Facebook employs. Did you know that Facebook uses your phone’s barometer to verify what floor you are on? Thanks to that and reading out the router’s MAC address Facebook will decide whether you share a flat with housemates or with family (also defined by your relationships of course but it starts all with the router’s MAC address and altitude). That’s sneaky and you can not really block that. 

The only way to block that is to give your modem/router a new MAC address and log it in via a VPN first few times you go online. Make sure to use the same location for your VPN each time as the system will lock the router to that location after few logins. Nobody knows this happens but for Facebook it all adds to the demographic profiling via much sneakier stuff than interaction. ;)