If this succeeds, it will be a data collection tool the likes of which the world has never seen, which is why so many companies are willing to put their name on it. The data, along with ML/AI, and our contemporary understanding of the human mind, means that this is a major step towards control that we can't understand.
Dr. Harari explains it better than I do in "21 Lessons for the 21st Century", but this tool is part of a suite of data collection utilities that will be dissected and used in order to further subjugate our mental energies to the will of the tech giants running our phones. If you don't believe that this is already happening, hang out with some teenagers. I would say that there is a large contingent of people for whom this is already true, and once that group is large enough, then how can you assert yourself against that pipeline of information?
Every bit of data we give away for free is a massive mistake. I hope that Europe figures out a regulatory framework that works.