Why ?
Easy, because there is no curve, when water is flat and cover 2/3(+) of earth, how would it work ?
Flat water - flatish earth, gives a plane, not a ball.
How can anybody who have been looking for the curve, made tests like the moonshine test ever go back to the globe ?
It is impossible.
When you then starting to look into Nasa, you have to say goodbye to the ball.