Everyone has too much damage, especially those who build full tank

Blame damage amplification in masteries.

Support and ADCs have too much damage? Tanks have too much damage? Do you realize it takes like 2-3 rotations of spells for a tank to kill the squishiest targets? that's like 7-10 seconds. ADC's don't do massive damage till 4 items and Support only do damage if they build like a mage or its lvl 1 and they have good poke.