You wouldn't put zero CD Manaless heals, speed boosts, slows or silences in the game...
Because that would be super anti fun and offer no windows of weakness.
So why do we have no CD Manaless dashes?
5 Comments
low cd, no mana cost silence
low cd, no mana cost slow
low cd, no mana cost Heal
I'm pretty sure lifesteal is a zero CD manaless heal. 
has a zero CD manaless speed boost, her passive: so does 
on a skill with no CD or mana cost. 
has a zero CD manaless slow, also his passive. There are only a half-dozen silences in the game, so no examples there, but I can find them for stuns (
) and roots (
).
is BS, but the comparison is invalid.
YOU WOULDN'T DOWNLOAD A NAMI.