The problem was political

The loss in the eyes of the Jewish people of rabbinic authority and legitimacy over time came from halakha’s inability to deal with history. The material forces governing the power relations continually shaping the Jewish people's circumstances were beyond the ability of the rabbinate to manage. 

The problem with halakha in the pre-modern and modern eras was political. It was in the weakness of the leadership's conception of their own possibilities. Assimilation was the natural response of the people to this powerlessness that was manifesting in rabbinic authority. Assimilation is not a failing of the people who are leaving the fold; it is a failure of Jewish leadership who seem not to be able to offer the followership a proper sense of national solidarity and integrity.