There's no pinpoint definition of how Smash should be played.
Exactly. Brawl, and the other Smashes were made to be played however you want. If Items were meant to be on, we couldn't take them off. Tripping was meant to stay on, hence why we can't remove it. Not all Stages were meant to be on either, or any Item, as we have the option.
Yes, it's true Sakurai thinks it's the most FUN to play FFA with Items and all Stages. He did say that. What isn't true is that he thinks people should not ever play it differently. Fun is subjective.
I think competitive gameplay is a lot of fun, and play that kind of stuff too. I hate the developer's intent argument, as it's bullcrap since it really has no effect on the community whatsoever. This isn't like hacks, which yeah, are different. We can do all this, have only specific items and stages on, and have fun with the game. There's nothing wrong with that. Also, don't mention Wi-Fi, as it's laggy, and is not indicative of balance either.