Darius isn't nearly the stat bomb that Yasuo is. Yasuo gains so many more free stats than Darius' extra AD after stacking 5 strikes of anything. Again, it's not about beating him, it's the sheer quantity of things in his kit. His win rate could be at 15%. His kit isn't any less overloaded. Apdo/Dopa (and please don't try and be like those edgy kids who have to try and diss critically acclaimed pro players) himself stated that Yasuo is horribly broken with his kit, the only thing holding him back is cockiness when you're ahead in that people get too aggressive and too full of themselves. The direct, translated quote (He's Korean after all, this happened on stream) is this:
"Bullshit aside Yasuo is a broken champion. People say he's a high skillcap champion, but the secret with Yasuo is knowing how to control yourself while playing such a overpowered champion. Yasuo's weakness comes from the fact that he is too strong. His laning phase is so strong that after the laning phase people do not know how to keep calm and throw the game."
https://www.reddit.com/r/leagueoflegends/comments/545try/apdos_thoughts_stream_after_hitting_rank_1_korea/ for reference.
It's towards the middle of the many things he said during this particular stream, just Ctrl + F "Yasuo".
His damage isn't the problem. His tankiness isn't the problem. Not the mobility, not the damage mitigation, not the build path. Not the way he scales almost purely off attack speed. Not the zone. Not his amazing synergy with any champion with a knock up (With some being very generous, such as Thresh's hook) It's all that combined into one perfect kit.
I personally don't have a problem with Yasuo. I play Zed. Even with exhaust, it's often a hilariously easy lane for me. I am not usually affected by Yasuo, but I can recognize his overloaded kit. Even if I usually beat him, I still recognize that his kit just offers too much in too many departments. He's sort of like a jack of all trades, master of most.