....I'm pretty sure that's not true, like, at all, but I could be wrong. Where did you hear this or find out this info?
And yeah, you're right about the ehternet port.
During one of the many debates about Switch online and the lack of dedicated servers, was like a year ago so hell if I remember any specifics. I see how it could make sense though, when playing a 1v1 game like For Glory, dedicated servers would be a extra connection point the signal has to pass through. It's mainly worth it with more players as there's bound to be atleast one with shaky internet. I could be completely wrong though, and even if not, dedicated servers would still be good for 3-8 player smash.
I'm a novice at understanding this kind of stuff as well but I don't think that's how it works - the dedicated server should be somewhere between the route that the signals were going to anyway, so for example it would probably pick the closest server in between both connection points, whereas in a 1v1 with peer to peer it would just pick one person's internet as the host and they'd have the advantage. And as you say, dedicated servers would be great for shaky internet, which can also go for 1v1 matches, if say someone is playing in Mexico and someone else is playing in Japan. But hell, I could be wrong., no biggie either way.