Games are codes. Game play is the act of code deciphering by players.
Having sat through classes in cryptology and played many games, I have no idea what you mean by that. You could say they're both generalized computing problems, which I might contend in the case of games, but they aren't simply isomorphic.
He wants group collaborative storytelling. That can't happen in games.
I think this is a silly argument; the disagreement between you is not about whether group collaborative storytelling can occur in a game, but about what the definition of a game is.
And different difficulties and imbalances between players is okay, because the game is designed as a cooperative game.
That seems to beg the question. All the people arguing in this thread that it was not okay understood that RPGs and D&D are cooperative games.
This is never a rule on how to play. Never does the game say "You MUST cooperate to play this game".
That's an incredible claim. Never do cooperative games say you must cooperate to play this game? Never ever?
D&D 5E Adventure League Player's Guide says: "No Undermining of Other Characters During Adventures. Adventurers are brought together by common cause, and during an adventure, they’re expected to work together to overcome challenges. Though certain factions might find others distasteful, individuals will put that aside and become a team when put in dangerous situations. In short, play nice with each other when things get deadly."
TORG Basic Set Rulebook (1990) says "Not all characters need to love each other, and you may even want some dramatic tension between them, but there has to be enough chemistry to bond the group together through all of the travails and troubles ahead--after all, adventuring isn't as much fun if you have to do it alone."
Sentinels of the Multiverse says "Sentinels of the Multiverse is a cooperative game in which each player plays as a hero with powers and abilities in the form of cards. ... Ultimately, either the heroes will successfully work together to defeat the villains and foil their plans, or the villains will triumph, and the heroes will be forced to regroup to fight another day."
D&D 4 PHB says "D&D is a cooperative game in which you and your friends work together to complete each adventure and have fun."
The line between rules and suggestions may be a little fuzzy, but at least the Adventurer's League is entirely clear that this is a rule.
Just like any cooperative board game or card game competition and individual play are also a part of expected play.
There are semi-cooperative board games where competition is expected, but Sentinels of the Multiverse, Pandemic, Hanabi and Forbidden Island certainly don't expect competition, and being competitive would be a good way to lose those games. The biggest complaint about Pandemic is the lack of individual play, that it often turns out that one player functionally runs the other characters.
There is a great deal of uniformity of thought in "RPG theory" today and silence in opposition to it. Most of it has to do with widespread ignorance mainly,
That's a good way to get me to tune out, when you suggest that everyone who disagrees with you in a subject is ignorant walking in blind conformity.