What's the point of bot lane if a solo lane can 1v2 a support and ADC?
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That's why you go carry support. The adc is just there in case the game drags to 30 minutes.
I agree that the adc role feels weak, but honestly supports are pretty scary, like if you go for a gank and the ali messes you up while the adc is AAing you it can hurt
Some ADC’s can very easily snowball and win games hard, adc’s like Vayne, Draven, Lucian and Kai’sa can hard carry the game and easily win the game for their team. Ashe is also one of my favorites because she doesn’t need to be fed to be semi useful to her team, she is more utility based and can slow the enemy team and stun them to help her team get easy picks.
And some supports can heavily influence the game too, like Soraka, Brand, Sona and Pyke. Soraka has her ult to give a big heal to her entire team, Brand has a large amount of poke during lane and is a very big threat in teamfights. Sona can stun and entire team and can give lots of bonuses to her entire team too. And Pyke can snowball very easily with ult and can get lots of easy kills.