While I agree that drawing and making your opponent discard will give you an advantage in a limited game, I would argue that it has nothing to do with Tempo Advantage.
For example, if your opponent plays solid aggressive allies on turns 1, 2, 3, and 4, while you spend your turn 3 and 4 playing discard and draw abilities, you haven't gained tempo on your opponent at all, and you will likely still lose, even though you have a hand full of cards while your opponent has none.
Discard and Draw are best described as examples of Card Advantage. It is one of the types of advantage that can help you win a game, but on its own is rarely enough.