It’s probably that with a lot of these games, the wiki editor(s) just don’t know what kind of servers those other games used. Anyone can contribute to the wiki.
But the idea is if it used only Nintendo Network (NEX) it will be supported at some point.
But if a game used 3rd party servers, it might be possible depending on the game itself.
But those would have to be assessed on a game-by-game basis. And only developers would know what would be doable (or have the resources to find out).