But Jos, they already Are travelling flat-out when they're hugging the outside. There'd be no point at all in going even wider since they're already at full throttle. The only thing they'd do would be to give themselves more ground to cover.
From drivers' point of view, you often hear them saying that a corner is effectively a straight, i.e because it's taken flat-out.
That's what makes the Parabolica so unusual, because it begins as middle-speed corner and opens up throughout. From their point of view the straight effectively begins as soon as they leave the inside because they treat the outside as a straight.
There'd be no more point in running even wider at the exit of Parabolica than there'd be in swerving around on a straight.