Why does Tahm do so much damage with almost no drawbacks?

His biggest move for damage is also one of the best CC moves in the game and is Q does a ton of damage too. And it's not like he's build squishy for this damage either. I think when he eats people his max damage should be 20% their hp no 32% (just wtf is that riot?) It also doubles as an engage tool and a MS boost. It's a really loaded ability.

Then he has a massive shield too because you know the tank running around in your front lines and eating your allies needed more tankiness and if he doesn't use it, he gets sustain. And then there is his ult. It has that stupid passive that adds even more damage for building tank. Just why. Why Riot why. I was taking 500 damage as an ADC being eating by a Tahm with 2 tanks items at level 16. I'm sorry but that is wrong.

I'm sure the only reason he isn't played that much is because of a lot of the ranged supports and his awkward early game. But making a support that just doesn't die and do a ton of damage is a problem especially when he has a better TF ult.

The one I just played against was jungle with Devourer and full tank yet he did more damage than their ADC. Okay Riot. Okay.