There's no two ways about it, adc is horrible at the moment. The champion.gg page for adc (which i encourage you look at for yourself) is pretty much the same for every elo and it shows that there are 4 marksmans with winrates higher than 50%. The other champions that make up the "viable" (for lack of a better word) adc champions are mages with high base damage and melee carries like yasuo and irelia.
So, my question is; "Why can't adc just be a viable role?".
High elo mains of adc are flocking away from adc or toward these new strats trying to find something that is impactful because marksmans just don't do enough early (which is fair because they are supposed to carry late), but then the marksmans don't carry late. Thanks to duskblade and stormrazor, ad assassins kill marksmans in one auto attack (to which there literally is not counterplay) and tanks are unkillable thanks to the build that is necessary to kill them being underpowered (for getting through massive amounts of armour and hp like it's supposed to) and overpriced for what it provides.
I thought that the changes to essence reaver would make caster marksmans stronger (which it did in the case of exclusively lucian) and that the changes to infinity edge would make hypercarries stronger. But they didn't because the cost of the core build for hypercarries went up by almost 1000 gold and the assassins (as stated before) make disgusting use of stormrazor so even if marksmans had the damage to scare tanks, they would not have time to do anything meaningful. This is also true of the caster marksmans because they don't have the damage to kill tanks on account of building very little penetration and their damage is not fast enough to protect them from assassins.
Even in professional play, marksmans are seeing a decline in play rate which essentially means that without a coordinated team, a group of champions that 1/5 of the player base main and should be in every game given the role they play in team comps is unplayable.
So... Why can't adc just be a viable role?