Its been kind of trending that way for years.
The main thing in season 8 that triggers the fighter apocalypse (or is it the opposite of that?) is the removal of pretty much mandatory defense runes before that everyone ran. This dropped time to kill across the board. And it doesn't favor the guys running out with melee weapons in a gun fight. There are guys are... in. weird. melee tanks though. These guys are still blowing up things they touch because relatively their base damage got buffed comparitively while they still purchase their added item bulk ups.
IN ADDITION TO THAT. Most tanks got a fantastic keystone. While bruisers barely get one they can call their own. Unless they go full blow me up precision. But doing that as a melee carry is playing league in hard mode pretty much especially when you fight amazing tanks and ranged every game.
And stepping back even more. ADC which beat down on the melee classes have pressured some buffs oughta riot so they can stay on top. This happened because of some early 2017 adc meme where adc were mostly picking utility bots and having a hard time scaling up against tanks. ( The adc problem, imo is the role just isn't fun or impactful unless it's overpowered breaking its fair boundaries. ADC player rates decline as you go up in ranks. The way it's designed and with outside lane into bot lane influence and support dependence well I have said they might as well be played by robots or that's what it felt like during the early 2017 adc meme tier. But when adc's are overpowered it's all well n good. this is the perspective of someone who can play all positions at higher ranks. digressed...)
Fighter items are helluva expensive too. They are sort of a little bit more powerful slot for slot though..? Sort of.
Fighters lose sustained dmg carry items like sated devourer turned into rageblade. Then turn that guinsoo's rageblade into an item with equally prohibitive melee/ranged stacking mechanics (in otherwords ranged only). Wits end rebalanced and repurposed for magic dmg dealers mainly and these guys are mostly ranged. They even tried to give triforce 20% crit once upon a time.
Its come to a point that unless you can lean on balanced tabis
you're not tanking much with offensive fighter items. And fighter characters are expected to build these expensive and riskier builds.
And Gnar is a thing. He singular obscures a lot of fighters. Even though he is somewhat weak to super hard dive AD fighters (ex. wukong. and only in early lane). The problem is that kind of champ is just not at all viable in a pro level team game. And what if the monkey was? Is that just more broken?