Why do aryl halides undergo electrophilic substitution reactions at $o-$ and $p-$positions? Why are they less reactive than benzene?

(N/A) Aryl halides undergo electrophilic substitution reactions such as halogenation,nitration,sulphonation,and Friedel-Crafts reactions. The halogen atom,due to its lone pairs,exhibits a $+M$ (mesomeric) effect,which increases the electron density at the $o-$ and $p-$positions. Therefore,the incoming electrophile is directed to these positions.
Aryl halides are less reactive than benzene towards electrophilic substitution because the halogen atom is highly electronegative and exerts a strong $-I$ (inductive) effect. This effect withdraws electron density from the benzene ring,thereby deactivating it. Consequently,electrophilic substitution in haloarenes requires more drastic conditions compared to benzene.