Riot has been fueling this ranged vs. melee arms race from the beginning:
is permakiting all our dashless melee champs? Melees need better gapclosers! 
Melee champs blowing up ranged champs in a few seconds while being unkitable and unkillable? Ranged need more tools!

Ranged are outdamaging melees while being unkillable? Melee need more reliability!

Point and click duelists are destroying other melees in the top lane? Melee need more versatility!

Marksmen can't deal with all these bruisers hopping around? Give them the mobility to keep up! 
Melee need more lockdown!

More gapclosers! 
Hey, don't forget ranged mages! They need tools to deal with overloaded melees jumping on their team!

Supports too! 
Damn, all these ranged champs are impossible for melees to get to, and even when melees do somehow get there, they just end up getting CC'd and die. Let's give melee a ton of gapclosers and burst so that doesn't happen. What, that would be too much? Nah, anything is balanceable, just take it out of their base stats or something.

Wow, ranged supports feel horrible having to peel these instagibbing, hyper-snowballing monstrosities. Let's toss everything we can into their kits too! 
At this point, Riot are starting to realize things are out of hand. They decide to dial back their release schedule so they can start to assess what the hell is going on, and figure out why people hate their latest releases. But the fun doesn't end here...
ZenonTheStoic: Yeah, sorry, I totally forgot to make his Q dodgeable. What, fix it? Do I look like I'm on the balance team or something? 
Gypsylord: She's immobile, therefore in exchange she should be able to do literally everything. Counter her? Just pick my other champion, Vi. 
CertainlyT: Check it out, he can go ANYWHERE and outplay ANYONE! Am I a genius or what? What, overloaded kit? No, you are clearly too stupid too understand my grand design. 
Gypsylord: Woaaaahhh, dude... I was just thinking... You know how marksmen counter tanks? Well what if we made a marksman... who's ALSO a tank??? No, not Urgot. 
ZenonTheStoic: High skillcap = good design, right? 
CertainlyT: *Hmm, marksman marksman, how the hell do I design a marksman? * plays some Jinx Wow! I did so much damage! But I really hated that part where a melee champion got in melee range, or a mage landed some skillshot CC, and killed me. 
Then the Juggernaut update happened. If you've been playing League in the past 6 or so months you know the rest.