Riot believes that adcs should melt tanks in the early-mid game.

riot wants adcs to always kill tanks unless the tank gets point blank and then the tank out damages the adc when it comes to max hp% shred. they also want assasins to kill backline with no counterplay to be had by the adc so the support has to hold their hand. and they want bruisers to be cc imune with such op healing GW does nothing to it so you have to somehow stun them in the 4 seconds between their cc immunity cool-downs.

tl;dr supports cant do anything but get blamed for not being perfect and solocarrying and mages are worthless 100% of the time