Marshall, I think you may have inferred a negative tone to my post that I was trying to avoid. I see 4e as very playable in a very gamist mode, but I don't see that as a bad thing at all!
Wealth by level and expected magic items are DM tools to judge the power of the party and in doing so be able to create the desired challenge level. Thats it. Its the overwhelming strength of the system that the DM can know "This level party with this equipment can do this level challenge while expending these resources." Even better, its accurate!
ermm....yes?

That's kinda my point.
Thats not true. A 12th level PC will mop the floor with 1st level monsters in 4e. They just wont normally face 1st level monsters. The main reason everything scales in 4e is so that the d20 stays relevant vs level appropriate challenges. You still outlevel early opponents at the same 5% per level that D&D always has. Except now you have the option to fight the same Ogre as a level 3 solo. level 5 elite, level 7 standard or level 9 minion and you get to feel bad-a** because the bad guy that took the whole party to take down at level 3 goes down in one shot when you are level 9. And the DM doesnt have to worry about that ogre being no real threat to your resources with a functionally -30% chance to hit.
Mario stays the same, because all his opponents stay the same. The only thing that changes in Mario is the world around him.
ermm....yes?

The 4e rules (at least the copy I have) strongly advise the DM to keep your PCs on that treadmill (although not in those terms, and I'll allow that later 4e publications may have amended that). Even to the point of simply "leveling up" or rewriting adversaries at higher level (the big advantage of that whole enemies are not PCs thing, IMO.) As you note, those 5% increments are (generally) applied to the foes as well. Mario just skips the treadmill math part. My only personal objection to the treadmill is that its a lot of math for little gain. Someone around hear suggested just skipping the 5% increments for leveling and just use HP to determine level...that seems a whole lot simpler to me.
No, its gamist because its measured in levels. That is a the core gamist conceit in D&D. Class and Level.
I'm not sure "Class" is a gamist conceit, but level certainly is...at least as D&D usually has it.
The only way to make those levels meaningful is to make them mean roughly the same thing. Which lets the DM compare them to other markers and run the game. It also lets players know where they stand.
I would disagree that its the only way to make levels meaningful. Even in the older editions, where levels came with different XP values, etc. gaining a level is usually a meaningful thing mechanically. The other things you mention are (to my mind) significant "value-added" propositions for keeping levels relatively balanced amongst the classes, but certainly not a requisite for meaning.
Sure, challenge level/difficulty level is a DM tool to run the game. Its not an indicator of playstyle or anything else.
I think within the context of trying to evaluate rulesets in GNS terms (something which is a no-no, but often indulged in), saying that game X has levels, challenge ratings, or difficulty levels of the type which we are discussing is fairly indicative that game X probably is somewhat gamist, at least in comparison to a game without those things.
Even in a Sim game(ALL games are Sim games), the players also need to know the challenge ratings or they cant make informed decisions on how their character should react to the world at large.
Whoa there! All games are Sim games!?! I know some Simulationist die-hards who would argue harshly against that point. (Although, I honestly think the Simulationist Definition is somewhat weak and people seem to be stretching it nowadays. So for some definitions that might work.)
However, players knowing the challenge ratings of foes and the like would be
against Simulationist play agendas, I would think. At best, the idea that all possible encounters can be numerically rated is Simulationist-neutral.