So the question then becomes, why is the game program no longer writable in the current generation? I'm guessing because random-WiFi matches use one of the two games as the "server" for these matches, rather than actual servers running them? They're worried about hacking?TheMaskedNitpicker:
Presumably, so-called "patching" was possible with the Ruby and Sapphire Game Paks because the game program was writable, albeit through more complicated processes. Probably, the DS games couldn't be updated in the same way because the game program is read only in the Game Cards; thus the only way to "update" them is to release new versions of the Game Card in stores, which is normally not obvious to users.
If that's the case, it would also explain why disconnects don't count as a loss for the disconnecter and a win for the opponent. Of course, Nintendo/GameFreak's extreme incompetence concerning online functionality could also explain that.