ADC complains about doing no damage to a tank while enemy ADC shreds our tanks
No
or
in our ADC's inventory, enemy ADC has
and triple our ADC's damage to champions
No
or
in our ADC's inventory, enemy ADC has
and triple our ADC's damage to champions
-builds no armor pen-
QQs when people are too tanky to kill

Reminds me when I started a game in aram as an adc and 4 enemies were tanks... I said "Fuck this" and started the game with last whisper. Strangely enough, it did more damage than I'd expect with a BF.
"I SHOULDN'T HAVE TO CHANGE MY BUILD, WTF IS THIS BULLSHIT? GARBAGE BRONZE%%% TEAM OMG" -ADC Probably
Tanks? You mean punching bags?
It depends on what champion you are too. Sure Armor Pen matters, but some ADCs will shred tanks better than others regardless of that.
Vayne can eat tanks. Given the items you listed their ADC as having, was it Vayne? Most ADCs can't build BotRK first, but she can. It would be trash on most of the others.
You also don't mention at what point in the game you are at. Sure you can add Pen as your second item and that will make you better against the tank, but what about the other 4 champions on the enemy team? You might be badly gimping your damage against them to do it building LW so early.
Being able to kill their ADC or mid might be a lot more important than how much damage you can do to a tank.
Played URF as Nasus on the PBE. When they /eq I immediately realized why they were so tanky. Building
and nothing else. A
solved that problem. (Nasus is an ADC right)
and in arams im the adc going yeah they are tanky but warwick why you ripping on me for getting the ability to survive but just feeding yourself to them (dead= no damage)[zombie-brand-facepalm]
Its only possible when you are vayne, kog, twitch, or ezreal. Ie and crit is more expensive than your chinese price defensive items
I agrea that marksmen are in an really powerfull state. It does count the same for dps tanks tho. It's probally more that the other role are just in an terrible state. #supports#mages#assasins are in the worsed spot. Hopefully mages get the fix next patches but after that whe still have 2 to go.