"Activist Investors" is not the same as "Active Investors". The former generally act for all shareholders while the latter, generally act in their own interests. The two are often confused.

As long as directors and managers "proxy" ownership of the corporation away from shareholders and to themselves (but leave the cost and risk of ownership with legitimate shareholders) then it is reasonable to expect those shareholders to agitiate against the board and management. It has been long demonstrated that both directors and managers act in their own self interest.