Why Benzene Cannot be chlorinated using HOCl?
One possibility:  When you chlorinate with, let us say, $\ce{Cl2 + FeCl3}$, you generate a "leaving group", $\ce{FeCl4^-}$, that comes off easily because it is highly polarizable and only weakly basic.  The $\ce{HOCl +H^+}$ combination would have to displace a more strongly basic and less polarizable water molecule.

Chlorination can be effected with hypochlorous acid by adding silver ion as another catalyst/co-reagent.  See here.