Oh look, ADCs are literal gods.
We're goinna call them weak and then buff them -- we care about our game beyond money though guys! Not like ADCs are the most profitable class or anything and are intentionally kept broken because of that... nah.
Sure is fun to be right clicked on and take 700-1000 damage twice a second no matter how much armor I build, while said braindead clicker sustains more than literally any champ in the game ever has -- yet, we've nerfed Vlad into the ground because of his sustain, and removed sustain from AP champs as a whole, nerfed champions because of their sustain... yet ADCs are exempt from all the rules.
At least they have all the counterplay in the world! You either:
-
A: Go nowhere near them so that they can't hit you.
-
B: CC them until they die.
-
C: Kill them so fast they can't even react.
or, the most likely scenario,
- D: Die, since you can't out damage their healing and you can't build items to stop their damage at all.
Really gotta wonder: If a champion's kit is so retardedly broken that the only way to fight them is to entirely prevent them from using their kit, then wouldn't that kit be too strong? Wouldn't it make sense to nerf it or rework it?
But, you know, ADCs work very, very hard for their damage (trust me, right clicking is a fucking art form, and most ADCs develop severe carpal tunnel and stress on their tendons from all the effort they put in), and deserve to out-assassinate assassins, out-draintank draintanks, out-burst mages, and generally be the strongest, most reliable champions in the game. And hey, almost all of them have some form of mobility, CC or both!
Oh how I love this game and company. I can sure tell they put the quality of their game above all else.
? pffft), no burst damage, no attack speed. You're basically a fucking joke. Ok, you hit a teeny powerspike on first back, if you have farmed well enough to get a 
and then another one when you finish your attack speed item and 
. But you really have to hit two or maybe three completed items before you start to be actually powerful. This is because, unlike other kinds of champions, you don't have a true spell rotation. Yeah, you have a couple of utility spells, tiny little bits of CC, micro dashes, traps, pokes, or whatever. But Brand or Veigar you are not. You can't just shit damage onto people, you rely on your auto attacks, which means you have to buy enough items to empower them. That takes time. Meanwhile...
and don't want her to snowball into a demigod? Play 
support, or 
so you can kill them every...what's the cool down on his Q, like 19 seconds? I've played it enough and it usually works wonders.
You know what else works well if there's a lot of life steal? Grievous wounds items 
and 
. Nothing says , "fuck you" to someone building 
like a big fat passive that basically makes all healing a joke. My sincere condolences, 
mains. CC works well too, as mentioned. So does burst damage, despite what you say. Nobody can life steal through a full 
rotation. And God help the ADC who stands next to 
when she drops Tibbers. You, my friend, are royally screwed. There's also a fed 
, about whom i have nightmares. Oh, you want to try to position and kite? Here's a nice wither, and a spirit fire, and an Q with about a trillion stacks, and oh look was there an ADC there? I'm just saying there's a lot of champions built into this game with the ability to terrorize ADC's unless their team is hella good at peel, and the ADC is hella good at positioning. 
come to mind especially, but really any of the assassin/diver types can do the trick. That's what they're there for.
or 
B) CC them. Correct, and it's not anywhere near as hard as you make it sound
C) Burst them down...which describes the play style of about half the current junglers, and most of the midlaners in meta.
or
D) Die because you didn't do anything to stop their slow build to power in the early game, haven't gained enough objectives or map control early on (because let's face it, tons of League games are over WAAAAY to quickly nowadays) to basically trap them inside their base well before they get powerful at about minute 35-40, and haven't picked a good team comp.