At this point, it's hard to fix everything that's fucked up. There's just too much.
Everything since preseason 7 (or even just the end of season 6) has led up to this point.
It's a long chain of events starting from whatever led to the assassin rework, which led to the lethality buffs, which led to the ADCin2017lul, which led to the ADC and support buffs, which led to the tank buffs, which led to more lethality buffs, and somewhere in all that, bruiser buffs and mage changes were thrown in.
And for some reason, any time a champ is said to be under-performing, riot just throws more damage into their kit, as if that would solve the problem. It's been going on like that for so long that there's too much of it.
For example, Lee Sin. "Oh wow we removed tracker's knife. We just nerfed Lee Sin. Damn he's missing some core utility to his kit. Instead of buffing his ward hop in some way, let's just add some damage to his kit."
Or Bard. "Bard is really not meeting standards as an enchanter, catcher, or whatever the fuck he's supposed to be. Instead of buffing his heal with a cooldown decrease or a heal increase, let's buff his meep damage. Let's make him a damage support"