I'm not saying their numbers are correct but you are missing: Routers ( four minimum, Netflix data center, backbone isp, local isp, your house), TV, for many a streaming device which can range from the TV itself to a PS5 or gaming PC, and for many a soundbar or amp and speakers.
They probably took max load for all those devices and lumped that all together which, yeah max load isn't right and the routers should actually be split amongst many many houses but it is all part of streaming.