Who should go tank and who should go mage.....

I feel that top lane should be the most responsible for making sure we have a tank, if your primary role is top lane then you should have several tanks that you play as......maybe 1 or 2 assassins sure.....why well we all know that marksman is the primary damage dealer in late games, half of them have zero to no mobility so without a front line there really isn't much getting in the way of these pesky assassins of getting to us. Now here's the thing, if jungler goes tank or even support fine play whatever you want......but please have a tank for top lane.

Mage if you primary is mid, please don't have Zed as your main, unless you see Elise, or Ryze, Vladimir playing in the jungle/top lane you probably should be playing mage at the mid lane. What happens when you don't, well if the enemy team has tanks and say you went Yasuo mid, and we have no magic damage, if their tanks are smart they're just going to build armor, a mage is supposed to force the entire team to want to build MR so that late game, the Attack Damage Carry can get off as much damage as possible the more magic resist the tanks have more than likely the less armor they'll have.