Yeah, dragonflies have an attack of 6 and deal 2-5 damage... but their defense is 8!
A griffin has 9/3-6/9 and 25 hit points! And you don't need to buff your units when fighting dragonflies; they'll win quickly anyway!
They'll just fly up and remove the buffs. And after the attack, the griffin's serpent fly will definitely not have 9 attack anymore. 8)