Have you ever experienced the burning desire to just get the last word when someone has contradicted your opinion and their rebuttal stands there unanswered? It's deeply engrained in human nature to want to argue. It's the less couragous version of people looking to pick fights, and it lives in all of us. In some this urge burns so strong that they go out of their way to derail conversations, make ridicolous claims, and just flat out be insulting or abrassive so they can stir up a riveting argument about anything or nothing.
runqvist here is one of these people who likes to go looking for trouble more than the regular conversationist. Thus when you make the reasonable question why he bothers to stop by a Nintendo discussion only to be argumentative and confrontationally he immidiatly drags the conversation down to the level that there's nothing in the rules that says he can't do it. Obviously an irrelevant direction for the conversation, but luckily for runqkvist, someone will bit and explain why it's against the rules, which opens up another delightful avenue for disagreement.
It's worth noting that a clear and honest answer to your initiall question will never come from the keyboard of the likes of runqvists across the internet. As I suspect you already know, the acctual answer to your question : "So why come into a Nintendo discussion and post then?" is "I just love to stir up sh%^". Admitting this would immidiately render runqvists goals in this discussion impossible, and so will never happen.
tldr; runqvist is a troll