Earlier quoted context omitted.
Can I re-phrase your question? "Why do we allow people to voluntarily hand over their own information at their own will?" Sounds much different when its phrase properly and not accusatory.
If it said up-front "this data will be collated and eventually used to emotionally manipulate you", I'd agree with you that people give the information up of their own will.
Because I have yet to be convinced that knowing how open, agreeable, etc. someone translates into manipulation and the article did not even attempt to explain that, it just said this has some vague relation to Trump & Brexit and left us to assume it was a magic X factor.