Because it averages out. If it's a true coin flip, half the time you'll get 1 point and half you'll get 0. So it averages to an expected value of 0.5 points. 2 draws (at 0.2 points per draw) would only yield you 0.4 points. So if there's a good chance you'd draw twice anyway, it's a higher payout.

It only makes sense if you are playing multiple games against the same opponent. Let's say you get 2 points for a win, 0.5 points for a draw, and 0 points for a loss. If you draw both games you both get 1 point. But if you win one and lose the other, you'd each earn 2 points instead.