Leads to a digital model of a person, the decisions they make , connections to others, preferences etc. Throw in all digital communications, purchases, treavel (etc.)and you can then run computer simulations with said data with more reliable results.
You also now have datasets which enable you to target individuals for advertising, propaganda etc. to manipulate emotions. I mean what couldn't you do with a digital model of someone?
We haven't even gotten on to them collecting everyone's DNA…