Then I think you're not paying attention, or you've misunderstood. I just checked 5 different pairs of scissors here, old, new, cheap, expensive, big, small, and all of them have blades that curve towards each other. When you look at them edge-on while they're closed, only the tips of the blades are touching, and light is visible coming through the gap between the blades everywhere else. That way only the cutting point is in contact as you use them.