Have you tried it? If not don't jump to conclusions.
I decided to try it to see if it was BS (I expected to find that it was false), its not. Granted I used the highly unscientific method of personal perception. But having tried four games (1 on Ethernet, 1 on wifi, 1 on phone to wifi & 1 on phone to 4g) I can say there was a noticeable difference between the wired connection & all three wireless methods. Why? Who knows! But since my 4g provider is different to my ISP we can safely discard the "it's you net" & "It's the geolocation of your ip" arguments immediately.