Why doesn't Target Champions Only work with Attack-Move?

It's obviously needed as misclicks happen all the time in teamfights. You either hit a minion/ward with Attack-Move or you use Right Click and move forward instead of hitting a champion. Why doesn't this trivial feature exist?

It seems like an arbitrary and frustrating way of increasing difficulty. It's only harder in the same mindless way that it would be harder to play while my cat jumps on me. There is no additional decision making. It's just "oops Attack-Move just hit the minion" or "oops he just moved and I ended up moving forward instead of attacking him".

I'm all for making the game harder but do it in a way that requires intelligent thought and feels rewarding. Having more complex ability interactions or diverse build options on the path to mastery is great but making the game more prone to misclicks doesn't feel particularly interesting.