do you care to return to the discussion of the core mechanics involved and my discussion of the expanded level base and the ability or lack of ability for a d20 system to maintain integrity during that expansion?
I'm neither JC nor Umbran but will stick my bib in anyway.
I'm not 100% sure that I understand your mathematical concerns, but I think they don't have to apply just because the game has levels.
I can't speak for 3E because I don't know it well enough, but an idealised version of 4e wouldn't break down despite its 30 levels, because the DC scaling would ensure that the odds of success were more-or-less the same across the range of PCs - from untrained to expert - at all levels. (To put it another way: if success depend upon a roll of d20 + X being >= Y, then provided Y-X is constant across levels, the actual values of X and Y won't matter). In this sort of game, the function of levels very obviously wouldn't be to change the odds of success, but to take game play into new fictional territory - eg as levels are gained, certain monsters (eg kobolds) would no longer be mathematically viable to be included in encounters, while others (eg Orcus) would become viable for inclusion.
In various ways, 4e falls short of this idealisation. First, there are the controversial scaling feats needed to make the maths work. Second, and related, there are the various buffing effects the scale to various degrees and therefore interact with the overall maths in a wonky fashion. Third, there is the uneven growth in bonuses (because PCs grow only some stats, gain items with bonuses to only some attacks and skills, etc) which means that some bonuses scale at not much more than 0.5 per level, while others scale at (or close to) 1 per level. The skill rules try to cope with this by adopting different scaling rates for Easy, Moderate and Hard checks, but this has implications for encounter design and resolution that probably are undesirable (eg at high levels Hard checks will be out of reach for non-specialised PCs, whose bonuses are growing at a rate closer to 0.5 per level).
It's at least arguable that 4e, if it is to have level-based stat gainst at all, should have them apply to all stats every time, in order to reduce the Easy/Moderate/Hard DC issue that the game currently has.
An alternative option would be to drop level scaling altogether, and with it stat bonsuses, enhancement bonuses, item bonuses, etc, and rely on some alternative method to ensure the progression-by-level of story elements.
(And I'm sure there are other ways of doing 4e-style levelling as well.)