Well, this isn't a rant about how broken yasuo is, it is a rant about why people think yasuo is broken and what he was supposed to be. This is all from experience fighting against and as him.
So, I am in bronze 3 and a zed/gangplank main and i have fought against yasuo a lot. He is honestly a huge pain in the ass when laning against him, and is considered broken and somewhat brain dead??? well I will try to explain which elements of yasuo was broken and what I think he was designed to originally be (this is all from experience, no research done).
I personally think that yasuo was supposed to counter mid lane melee assassins like zed and Katrina (which he does very effectively) but he still needs skill to play and one trick. If I remember correctly, zed was very prominent during those times and was a problem ( seen heavily in pro play too). yasuo effectively does do what he was supposed to do as he is considered a counter pick for most of the assassins but riot went overboard as they realized that mid lane has mages and others too and most assassin's primary damage and set ups comes from ranged abilities (displayed in zed and Katrina) so they decided to add wind wall as a way to defend yasuo against mages and the assassins. Also his q literally denies cs from these melee assassins while staying behind his minions preventing the assassins from being able to burst him. his passive is also so that assassins like zed cant jsut use his weqw2aa combo on him and just kill him like that, also his extra crit passive was in my opinion to prevent him from being a 4 item aoe nasus q with 2 sec cd, but it failed and he is very strong due to it. His entire kit was supposed to counter melee assassins like zed but accidentally counters mages too like vel koz with his shitty ass windwall and his god forsaken dash, I'm guessing riot didn't expect it.
**Edit: its just a theory bc i play against yasuos everywhere as zed or gp, I tend to shit on them with gp but zed is a bit harder, so just my idea.**