The reason why True Damage exists is because it takes no skill to buy resistance and there is no way to outplay it. If you have 100 AP on Mage, for example, you still need to apply it. Miss every skillshot and it's wasted gold. But Tank with 200 Armor can just stand there taking enemy's hits, expressing no skill and fully capitalize on it. They need to accumulate gold like anyone else, just not express skill in using stats bought.
This is not problem If you have at least chance to outplay the tank's kit from range. But what were Fighters supposed to do? In melee range most of them would be inevitable victim to most tanks' entire kits who then win trade because they knew how to press BUY and have good damage even when not building damage as long as enemy doesn't build resistance, which they don't, as they are dmg dealer.
So Riot gave Fighters uncounterable wildcard stat to counter otherwise uncounterable wildcard stat and are also recently filling their kits with traits to mitigate heavy amounts of damage naturally, be more mobile and have more range control so that the Fighter could do something.
Could Riot implement a counter to that better? Yes, in the world where tankiness has skill expression rather than being that unkillable behemoth that throws in CC and wins fight. Where Assasins don't oneshot on the basis that you didn't get twice your HP worth of Shield. Where Enchanters cannot give you twice your HP worth of shield without skill expression. Where Burst Mage isn't dodgeball of one ability into death once you get hit once. Where ADCs aren't either better ranged version of the above or the champion that just clicks champion 'n ground repeatedly faster as the items go on. Where CC scales with skillshot range so champion either has range control or peel but cannot say fuck you to divers both ways. Where Fighters And Assasins can actually be hit instead of flying around big time.
But we're not in such wourld, we are in world of race arms of who got the most bullshit mechanic this year.
and to a less extent 
for this exact reason.
as my starting item. It's trash design that conqueror takes forever too come up or can be procced at the start of a fight. Fervor rewarded fighters and punished tanks for extended fights but now it's moreso about the matchup.
(in kit champion armor pen/ ignore / % hp damage/ increased auto attack modifiers 
etc)