First post in this forum, sorry for the wall of text, there is a brief version at the end.
Back in Season 4, when there wasn't a "tank meta", I thought that, at a fundamental level, some type of champions should roughly "counter" other type of champions to keep a general balance and fairness in the game, especially in team fights. The natural questions, at that moment, that I immediately recognized regarded tanks, adcs and assassins: (1) if assassins have a relatively safe laning phase and, during team fights, can burst any other champ (including tanks) in less than 1 second and somehow go back to safety (to rinse and repeat the process), this will make them unbalanced; (2) if AD Carries have too much health (fortunately, this will never happen), this will be a problem too; (3) if tanks have 5k+ hp, huge amounts of armor and magic resistance, and deal the same damage as a burst mage/assassin at the same time, with some CC to boot, then something is clearly wrong. The second point (2) is, luckily enough, only theoretical and the first point (1) is untrue in its entirety (though Assassins, generally speaking, can still 100-0 squishy targets by fully committing, but this isn't a problem per se).
Enter S5, where the "tank meta" became a thing. The third point (3) is actually becoming true, though I cannot know to which degree. The fundamental fact that should keep the mathematics roughly "balanced" should be the following: a generic champion "X" should never have both high damage and "tankiness" at the same time. Just like a Jinx with the hp/armor/mr of a full-tank-build level18 Nasus using Ultimate is a theoretical monster which breaks the game, there shouldn't be allowed an unkillable tank with the damage of burst mage/assassin (or more). Summarizing, the principle should be: either you have damage or you have "tankiness". But no champion should have both at the same time. With AoE and/or undodgeable CC added into the mix.
Some may critique that the laning phase is the weak point of tanks. This poses two problems: the first is that we are silently accepting that all tanks are now late monsters (the equivalent of a 1k-stack Nasus), which I can argue is not the best decision ("rise the puppy" now becomes "rise the tank"); the second is that it should be always taken into consideration that this is simply untrue: Nautilus Support is not a solo lane (and I cannot honestly say it is "weak"), jungling isn't like laning and, more generally, tanks do not always start in such a bad spot as to make them automatically lose against non-tanks.
The other type of critique which I would like to dismiss is "kiting". Although it should always be done to almost perfection, kiting is not the definitive solution to the "tank problem". If all tanks starts to magically have CC and/or gap closers (which all the mentioned tanks in the original post have) or very high movement speed, the effectiveness of kiting is greatly reduced (to almost zero, unless you are called Kalista, which is probably the only adc that can do "perfect kiting", i.e., keeping a nondecreasing, safe distance in an infinitely long escape path). Kiting is very effective when a slow speed melee enemy ("tank") tries to reach a high speed target with range ("sniper"), but it isn't effective when they can close the gap in 0.2 seconds and stun you for 1.5 seconds, probably dealing enough damage to kill you anyway.
Regarding CC effects, especially AoE knock ups and/or stuns, the tank problem is really apparent: mixing high damage, CC and tankiness can become explosive if some math of the game starts to change in your favor, escalating due to a butterfly effect for a single, apparently small, change in an item and/or a base stat of a champion.
In brief: In the set {high damage, high tankiness}, you can only pick one, minimizing the other. At least, in principle, since we can clearly see this is not the case as of now. Having a terrible laning phase, whether true or not, isn't a solution to the problem.
on marksmen, 
on your ap carries. also, if your teams tanks are good, then you should have peel to keep them off of you while you shred them with said items. there will always be a champ out there that can 100-0 any given champ in a 1v1. teamfight against these guys and place yourself out of range of the tanks and behind your own. a nice braum ult followed by an angry ali should give you enough protection from a malph/amumu combo.
