If earth and other celestial bodies in their static orbits were flat, space exploration efforts wouldn't be using them as gravitational slingshots to explore deeper space and other celestial bodies. Scientists and engineers wouldn't need to perform any calculations for satellites and ISS to keep them in constant orbit, at steady speed and elevation around Earth. We wouldn't even have them, because it wouldn't be possible to keep them up there if earth were flat FFS.
Introduce me to a flatearther and I'll introduce you to a moron.