Quote from PersonmanI want to agree with this, but it has the same problem as all honor-code rules - it asks players to voluntarily give up an advantage, and thereby rewards those who choose not to. There is no way to differentiate a player who starts thinking about their deck a few hours before the deadline, sees the "loophole", assumes everyone else saw it too and submits a deck that uses it in an attempt to remain competitive from a player who saw it during format discussion, realized no one else was thinking about it, and sat on it until submitting a few hours before the deadline.
Of course, in a friendly game where the moderator participates, we have to have an honor code, and we do, and it works great, because we are all good people. But I don't see why we shouldn't minimize it as much as possible. I know from experience as a moderator that it is easiest to do the job fairly when I make a clear distinction for myself between "format construction time" and "deck construction time". During the former, I try my very hardest to make the format truly airtight. During the latter, hopefully at least a few days later and thread discussion later, I try my best to break it.
I think that dichotomy should apply to everyone, and that no one should be punished for playing the game to the best of their ability. We should all be honorable while we are discussing the format, and I trust everyone here to do that. But once we've settled on a formal definition, all bets should be off - the joy of this game is in the creativity we all manage to display when trying to squeeze every last bit of value out of a format into a tiny little deck.
I respect the instinct behind asking players to "play fair", but I think it can only have unfortunate results - either the moderator will be put in the position of making an a fairly arbitrary judgment call about what the "spirit" of the rule really was, or players will shy away from submitting exciting, boundary-pushing decks for fear of running up against such a judgment call. As a player, I don't want to worry about making the moderator uncomfortable by submitting a deck - I just want it to be unambiguously legal or illegal.