The problem is that even one poorly behaving (h)activist sets a precedent for average people against all other activists including those that perform a societal good in a very ethical but technically illegal manner (Snowden). It also sets a poor example for others coming of age.

How things are accomplished is of more importance than what is accomplished. Activists should plan carefully by seeking out likely anticipated consequences before pulling the trigger. Otherwise, it's just reactive, aggressive chaos that doesn't go very far.