chogath has been almost completely untouched in years. no one complained about him during the assassin meta because he would die instantly, same with the carry meta. he finally has his time to shine because he can't be deleted instantly
as for balance issues, his damage is a little high, but if you change his kit any, it will really hurt his overall game performance.
he's actually a perfect example of what a tank should be: crowd control, first and foremost, then tanky, finally burst damage
other tanks that do this: amumu(who is a chogath counter), gragas(who was/is (idk since I don't visit these sites but its what others have said) 80% ban rate and 100% pick rate in professional play; sejuani (her damage isnt' immediate, but she can slow you almost indefinitely, has a twitch/kalista-like ability and an AOE stun. what's more, she can face tank, something chogath isn't smart to do.
singed: this guy is not what a tank should be...he runs AWAY from the enemies and has 2 forms of minor crowd control. his damage may be high while they're chasing, but a tank is not supposed to run away and is supposed to deal damage
let's take a look at the roles:
squishies: AP Carry; Marksman; Assassin
AP Carry: does large amounts of burst damage but has low sustained damage and typically low mobility (EX: the many assassins out there, but even some of them have way more than they should, fought a diana who could facetank 1k critical hits while still deleting any target and I think she had like 4k hp...)
AD Carry: large amounts of sustained damage over a range with versatile abilities to make them the high priority target but in exchange for their damage, are typically the easiest to delete
assassin: extremely squishy target with insane burst damage or rapid burst damage, yet some of the "squishy" targets are very difficult to take out. Zed for instance, the guy doesn't even need tankiness when he can harrass you from complete safety and make himself untargetable for 2 seconds
medium roles: fighter, support
support: typically most supports do not have high damage but can make up for it with crowd control, tankiness and sometimes one high-damage ability. Thresh for instance, typically built very tanky, can have very large burst damage and insane harrass with his area denial abilities (other examples include blitzcrank, etc) whose primary roles were created as tanks and fighters, but were later found to have better use as supports
fighter: the all or nothing character, can be built tanky, high sustained damage, high burst damage, typically low range or one long range ability
ex: shyvana: an all in fighter with a large amount of tankiness in exchange for her damage, but still deals reasonable amounts of damage. she has an auto attack reset to increase her damage output and deals damage over time while all-inning the enemy
ex: mundo: typically built tanky, dr mundo thrives on enemies' inability to kill him. He deals high burst damage on his Q, medium sustained damage on his W and medium sustained damage from his E. he trades his damage capabilities for the ability to stick to his target and harrass them as he "pleases"
the tanks
tank: as I mentioned: crowd control, high burst damage and tankiness(typically long cooldowns).
ex: darius: high burst damage, low range, high durability when built tanky and low ranged
Ex: garen: extremely tanky with large amounts of burst damage but melee ranged
ex: rammus: trades most of his damage (a mistake) for multiple forms of crowd control, high mobility and the highest armor rating in the game
if anything, I think all this proves is that riot needs to redesign their other champs so they can fit their roles. Someone posted that Ekko was being used as a tanky bruiser because of his multiple forms of crowd control, engage potential, reset button ult and the strongest shield in the game(even though it only lasts 2 seconds) while having high AP ratios for his mage-level abilities (which as a tank you can easily get 500 ap)