I get the technological restriction of how download+upload can't both be 20mbps if you only have 20mbps bandwidth possible, but I'm not sure as to why you can't have 20 in either one as needed, such that if you were uploading without downloading, you'd upload at 20mbps. If you were both uploading and downloading, 10mbps each, and if you were just downloading, 20mbps download.

i.e. IDK why they throttle the down/up speeds individually instead of the combined down/up speed.