You are right but missing my point mate. I know game changes every single day which is "must" to develop new chances etc. But here is my point,
back then tanks were tank. Realyy tank. I mean tank you know, bulletproof . People were ignoring them and trying to catch squishies first at low elo at high elo doesn't matter. Because even if they hit it would waste time+ you could get slowed pretty well because of the old Randuin's. Now its like hit the person whoever close to you anyway you will deal massive damage because you have at least Black Clever. Tanks, They had no dmg but could survive even after teamfights. Now with all those fancy shits they can't tank well enaugh. Jarvan example was just an example.
Riot doesn't want to see fights can last 1minutes and game gets too boring, I definelity understand even I wouldn't want to see too many tanks and see them op as a tank player in pretty much every game. But what i see, there is no point to survive against AD champs. About Mages, its still okay. After some m resist they don't deal damage much and they also shouldn't spend cooldowns on you. But AD champs are generally broken. For example "Hexdrinker" is pain for a mage. Do mages have kind of? Yeah they have Zhonya but wait.... Zed rushes youmuu's so whats the point of buying armor then? You buy armor instead of mana regen or ap which you need to stop zed but he buys ad at the same time armor pen which makes your zhonya's deffensive stat useless. THIS IS EXACTLY WHAT I MEAN. Generally speaking. Pure ad bruisers are okay they deal massive damage but anyway they die easily. But put some BC and some Randuins maybe youmuu's etc. What you get? A champ with 4khp not a real tank i agree, but does his job and even better than a tank.
let me do the math,
put away all the team comps, picks etc. Just imagine a teamfight.
there is a pure tank with 4.5k hp and 350 armor. And then there is a juggernout or bruiser call what you want with 3khp 200 armor but 250 ad.
Tank survives for 5 seconds and deal total 1.5kdmg lets say, bruiser survives for 2-3 seconds but kills one person and sometimes even get double. ( ofcourse it wont happen in 2 seconds but just an example also tanks are not made for dealing damage their job is making a chaos, forcing enemies to break their positions, cc's etc , i know. but im talking about the surviability.)