Part of the reason ADCs are so "strong" is that defensive tools across the board are too strong.
If you wanna get to the ADC nowadays you have to wear down the unkillable Cho'Gath/Maokai that can't be focused because of Stoneplate, and can't be sieged out of lane because of Warmog's. Once you get around that the ADC gets a Galio ult, Lulu ult, Shen ult, Locket, Redemption, Mikaels, Knight's Vow, etc.
It's getting incredibly frustrating to watch teamfight after teamfight at worlds this year where both teams completely fail to get a kill off of a flawless initiation and some players even manage to come out healthier than when the fight started somehow. The game has reached the point where you aren't fighting to kill, but fighting to burn through all of the enemy team's excessive defensive tools first.
This is why damage records keep getting broken by ADCs this year at Worlds; it takes a fuckton of sustained damage to actually kill something in this meta.
and
went from 45% bonus Armor penetration to 35% bArPen
went from 30% ArRed to 24% ArRed
, 180 AD, 1.52 AS of .656 base AS ) pre- and post 7.9, against a target with 80 base Armor (level 14-16 beefy melee) and Deadman's/Sunfire (100/120 Armor + 9 from runes + 6 from masteries):
), you have low damage to structures, (generally) can't do anything special against camps...
i would build it all the time because of the high amount of mr and solid hp it gave along with the fact that with the spell shield i could absorb a cc ability that would otherwise be a huge problem for me like
polymorph
ult
stun.