I just went back and read you first post and it was brilliant, that sounds like a good idea.
Thank you. Admittedly I can't claim credit for spawning the idea...another fighting game community already uses the 'social system'. It seems to work for the most part, though I have seen a few instances of false reports giving someone a bad rep. On the other hand, the people hurt by it seem to be an unfortunate minority; I've also seen cases of the system working exactly as hoped both in terms of keeping you away from DNF'ers, and helping you go "Oh, that other guy is legit. I'll play him!"
That, and it costs roughly $0.00 to implement since the fan community does it (and policies themselves, in theory). Nintendo is unlikely to invest any huge effort in anti-DNF measures, and technologically speaking there may only be so much they can do. So this might be the best way to handle it. Not the perfect way - I'm unsure if there is one - but possibly the best.
DippnDots also brought up a point: Such a system works better if you can present hard evidence of DNF behavior. This, I think, would actually be pretty easy to do. Videogames are deterministic; if you feed a set of commands into the game, using the same starting conditions...the results will be identical, every time. So Brawl could let you record Replays of games, using just an input-recording. The file-size involved would be very small, and if some sort of file-transfer utility were added to the Wii (or even just to Brawl, using Wii system friend-codes and such), you could produce some kind of proof.
Granted, even that could be prone to forgery; someone could pretend to be someone else and intentionally go on a DNF spree to smear them, but...there will be ways to abuse anything.
