[WS:] The CP would say that they invested the surplus to provide for the long term interest of the working class, instead of consuming it. Do you think that the democratic control that you advocate would accomplish that? Lenin would disagree (cf. his position on limits of trade unionism in What is to be done?).
In any case, ownership does not equal control of the workplace. Modern corporations are nominally owned by shareholders, who rarely exercise any meaningful level of control - the management does.
Wojtek