Eh it's debatable but I don't think this is entirely accurate.

WiFi is very good at maintaining maximum transmission rates. High power is needed when doing stuff like QAM64 over the air.

If wifi was louder than it needed to be, you wouldn't have to be mere feet away from the router to get maximum speed.

Wifi bands are saturated because there's so little spectrum for a widely used service. Everyone has multiple wifi transmitter in their house yet there's only enough spectrum for three non-overlapping channels.

Imagine there was enough spectrum for 30-40 wifi channels. There would be hardly any overlap and everybody would have better range. Maybe 500-1000 feet line of sight.