Technocracy starts with the success of modern science – precise measurement and prediction. This led to a significant increase in mastery of the external world which increased the material standard of living. Due to this success it led to scientific management of people. Since Newtonian physics onwards jettisoned formal and final causes, leaving only material and efficient causes, this led to belief that there is just matter in motion (a mechanistic view of reality). This was then applied to society which led to the idea that the only things that actually exist are the individual and the State. The institutions of civil society, in particular the family, simply no longer exist in a robust sense.
This then requires the State to manage society in a scientific manner. Experts in fields are then brought into the state to manage society. This can be also done by megacorps too who are effectively legally privileged. In short technocracy sacrifices individual and family autonomy in the name of scientific management.