This post is so true. AD items are so much more effecient than tank ones. Full tanks (some champs are exclude like cho with free hp and rammus who can double up on thornmail passive) just don't have a place in the game anymore
A game of full damage dealers will get SMASHED by a team with atleast 2 bruisers or 1 ultra tank. A tank/ 2 bruisers are so imporant they can by no means be deleted from the meta and not just of the initiation part of their job because there are some ap mids who can do the tanks job of iniitating better then the tank like lissandra. The reason you need this is because of aoe damage and survivability. A team with only direct damage will get deleted in team fights and if there are no tanks to protect the direct damage dealers then they will get deleted even faster. The job of like renekton is to pose a giant threat to the enemy adc/apc so they are FORCED to attack renekton and if they don't they will die meanwhile he doing damage to everyone around him as he attacks the adc because of his massive aoe damage so by the time renekton dies he did a lot of damage to the entire team and made the adc attack him and not his valuable targets. This gives his valuable teammates the freedom of dealing damage with a lot less danger.
Also, theirs the fact that if you pick a full damage dealing team the enemy will just pick fiddlesticks and get a very easy penta.