Not at 100% it doesn't (help me).
Go to the training range just stand in front of those first two bots and try to make a single turn with the mouse eventually crosshairs going over those bots, it will drag you down to a stand-still.
Next, climb that roof above the two friendly and two enemy bots. Try to snipe the group of 4 moving bots on the left side by dragging your scope downwards to their head. Your scope bounces off the aim assist like it's a rubber ball.
In a match, try to snipe a Mercy healing a Roadhog or another character with huge hitbox extending from his player model. Takes so long to manuveur around the aim assist that your team got 30 eliminations while you were trying

We nagged Blizzard so hard to get this option to improve quality of life (of gamepad users too to be clear!). I recommend to try 90%, 80%, 75%... anything but 100%.