Because the inability to grasp these concepts and others like it are the basis for many flat earth beliefs.For the record, I'm not asking these questions because I'm trying to prove any flat earth theory. I don't know why there are all these references to flat earth because I didn't say anything about that.
People have trouble wrapping their heads around this shit so they figure its proof of lies and conspiracy about the earth and its shape.
People who can't read are just stupid, but people who can't do math are a danger to us all.