Yes, which made the numbers completely irrelevant. In order to create a game that does not eventually "break down", you would have to design out +x bonuses. Diablo could have been played without any discernible difference if the only thing you got from each level was a unique ability, not bonuses. For example, the Barbarians leap ability. There was no + to hit, just the ability to ignore terrain to a degree. Keeping track of the bonuses was just mental ************.
You could create a game where all of your bonuses were defined at first level. Take your ability scores, add a race template, a class template, and a handful of discretionary +s to customize. From there on out, you would only gain abilities that broke the base rules by giving you unique options, such as Power Attack, Combat Expertise, Track, etc. You would have the same exact game as a static increase game, but without the math. I don't think it would be a bad idea, maybe even as a different take on the E6 idea. However, I don't think it would be D&D any more, and certainly not a D20 game.