TFT: Why play Assassins if you can just stack a Yasuo?

Assassins are meant to sneak to the back line and assassinate the carries. But Yasuo does that automatically, and stuns them while he kills them, which he can one shot if he's stacked with the right items. So it's no wonder no one plays Assassins anymore; just curious if Riot cares about this, or if this is just Yasuo's time in the meta?