Hussar
Legend
Yes, but that's not very helpful, as "game" is broadly defined.
It includes things with well defined rules and set win conditions. (Chess)
It includes thins with well defined rules, but no clearly defined win conditions. (D&D, though sometimes the rules get a little fuzzy)
It includes running around like a maniac in a yard with your friends. (Yes, Calvinball is still a game)
True, but, even within those three things, you still have commonalities - an agreed upon structure for determining valid and invalid actions. Even Calvinball has this, to some degree, since you simply come up with new structures each time.
And those structures are important. Without those structures, you cannot progress any further. Even in things that aren't games, like, conversation for example, you still have agreed upon structures for carrying out that activity - I stop talking when you start, I listen to you when you talk, I don't scream in your face or various other unacceptable things. In an RPG, you have an agreed upon framework for determining the results of actions that are important. Imbalanced rules obviously affect that framework and make progressing in the activity more difficult. Talking to someone who has no idea of how conversation should work is pretty difficult (and anyone who's tried to talk to a two year old can attest to that). Trying to play an RPG with imbalanced mechanics biases results. The more imbalance, the more biased the result.
Take conversation as an example. Let's add an imbalanced mechanic to conversation. Any time I touch my ear, you have to agree with what I am saying. Can we carry out an enjoyable conversation? Well, perhaps, if I only touch my ear after I know that you already agree with my point, but, more often than not, that's going to lead to a pretty frustrating conversation.
RPG's are no different.