Assassin right clicks you and you die. Yasuo misses his 'q' and is completely useless. So yea, it's f*cking hard to play Yasuo compared to these assassins. Unlike assassins, it's actually possible to dodge Yasuo's damage abilities which adds counterplay to him. And when he finally gets his damage items (his crit items), he doesn't even get to do 100% crit damage, so his power spike isn't even that big. He can't one shot you like Rengar, Leblanc, or other stupid sh*t in this game.