Tracking. Pure and simple. 5g uses higher frequencies that, because of physics, don't propagate nearly as far. They also get attenuated by things like the glass in a window. So less signal coverage = higher density of base stations = easier to triangulate someone's location simply from which station they're connected to. They can know what building your in from that alone, GPS no longer needed. In some densely populated areas, there are enough base stations to tell what FLOOR you're on. So they advertise faster speeds, but really they're just making it easier to track you without having to get a warrant for your GPS location.