"Back in the time when the Xbox One came to the market, Microsoft implemented an anti-piracy measure that consists on adding a unique code into the game disc, which prevents you to play used games on your console, but back then in the Xbox 360 times, the system was a little bit different:
If you inserted a brand new game into one console, and went online, the code would get registered in the Microsoft database, and to actually ban people, if Microsoft caught you with that same code on another console, you would get banned. So it is exactly the same strategy on the Nintendo Switch, but you can actually play those games, and they can get you banned, so now you know why if you go online you get banned"
100% BULLSHIT