if only an ad assassin could do that. sigh remember when ad and ap were equal? no i dont either.
AD assassins, by the nature of being AD, have better auto attacks than AP assassins. An AP assassin, with their skills on cooldown, deals next to no damage with their auto attacks. An AD assassin, with their skills on cooldown, deal a significant amount of damage with their auto attacks.
I don't think anyone can doubt that this is taken into account when a champion is being ballanced. Yes, flinging a bunch of spells in rapidfire and bursting someone down is flashy, but auto attacks can be just as dangerous (see Fed ADCs).