Teemo's Blinding Dart is a pretty clear example of "binary gameplay". Either the Blind is absolutely debilitating or it's next to worthless. I usually see it being more the latter, since most opponents will use their abilities, not basic attacks, to kill Teemo anyways.
If it were a Nearsight effect, Teemo could get a lot more interesting gameplay out of it. He could use it for brush jukes, prevent an enemy from seeing where he's putting down a shroom, etc. Plus it would be far more universally effective than a Blind, preventing enemies like Vladimir from nuking him for a little bit.
#Assume Riot would adjust Teemo if they made such a change (i.e. nerf him).