The power creep ("reworks" that increase power, keystones, items) is huge this season.
You don't need many damage items to 1-shot a squishy, and champions who aren't tanky simply get 1-shot. Hell, even tanks can barely survive late game fights.
The result is that anyone who isn't an ADC builds tanky. AP mages have more HP than bruisers now. The tank playstyle has become that of an assassin's: Get in, 1-shot the carry, and get out before you melt. It's a mess.
There is way too much free damage. Damage all over needs to be gutted. Then:
* Tanks will no longer 1-shot.
* Assassins will actually need damage items to kill.
* Tanks will actually survive more than 5 seconds in a teamfight.