OP used confusion, it's super effective!
Seriously though I can't tell if you're saying Darius is OP or UP. You say he needs buffs, then you say he's overpowered and list changes, then you say he's "the most mobile bruiser in game, again playing along with boards because his passive movespeed is broken and his pull makes him a god tier top lane". After that you collectively call the people on the forum trash and say they'll agree with you and you suggest he gets nerfed.
Here are some facts about Darius: He has the easiest kit to use in the game, the best AD ratios in the game, has an instant CD ultimate true damage nuke attack, a passive 30% AD bleed on every hit, a mass pull, a huge AoE that does 50% extra damage if you're in the last half of it, a slow that deals 100% AD as bonus damage on your next attack, said skill also has CD reduction per stack of bleed, passive 25% armor penetration, +5% Movement speed for every bleeding champion, 340 base movement speed, and gains huge armor, MR, and health per level naturally. Oh and the lowest skill level of any champion in League. It's a literal 0, look at it.
So yes, he's broken. He's a god in lane, and if he gets a kill then you might as well not go back top because he's going to get 3 more and take the tower anyway. And even if he doesn't get a kill in lane he's still going to rip everyone on your team a new asshole.
Things commonly heard when someone states Darius needs a buff:
"Oh but if he's stunned in a teamfight he's dead meat" No he's not. 1) The stun will probably last 1, maybe 1.5 seconds and then Darius will proceed to AoE your entire team, pull them back in, slow them with 100% bonus AD damage, bleed and AoE the shit out of them again, and the proceed to shit on their corpses by using his ulti on 4 different people because it has no cooldown. 2) 80% of the time you can avoid a stun if you play smart and aren't a dumbass. Sure some point-and-click stuns exist but most are skillshots or passive abilities. 3) THEN GET TENACITY BOOTS IF THAT'S A HUGE PROBLEM FOR YOU. JUST LIKE ANYONE ELSE.
"Darius can be kited so easily, it's not fair" Dude look at your kit, YOU ARE NOT FAIR. Your kit is so simple and overpowered that if I went to the zoo and gave a gorilla my laptop he could play Darius on Silver and have a 60% win rate.
"Oh no a ranged champion, I can't touch that as Darius" BS. This is purely a lack of skill. Yes they're ranged and you're melee but what do you think your PULL and HUGE AOE are for??! I'm sick of hearing this one.
And the worst of them all: "Darius falls off late game omg Rito plz buff" Where do I even start... there is legitimately no basis to this argument other than you're a terrible player.
But do you know what the biggest issue with Darius is? It's his skill level and simplicity of his kit. Darius has a skill level of zero, zip, nada, nothing. This means that he's decent in the hands of a bad player but is an immortal god of dunking death in the hands of anyone with skill.
I would complicate his kit, switch it up in a way that nerfs his early game but buffs his late game at the same time. It's the only way to balance him.