> The downward pressure that should exist is high earners retiring and low earners just starting their career.

> and the remaining 94% increase their earnings.

This is an extremely unrealistic expectation. There are a multitude of reasons for people's incomes to fluctuate other than retirement. People make career changes that result in lower income for many reasons, like taking a better job, changing careers, transitioning to a lower demand job when they have children, or moving to a new city with lower wages for personal preference.

For many jobs the earnings are also dependent on the company's earnings. Incentive structures, bonuses, RSUs. Even low paying companies scale their staff up and down based on demand. They can't hold a monotonically growing set of staff and also monotonically increase their wages when the incoming demand for their product is not monotonically growing.

The only way to come close to an "idealized society" like you're proposing is a totally self-sustaining, command and control economy where a central authority determines not only everyone's income, but their expenditures too. It's not possible to keep the entire economy and everyone in it moving in the same direction unless you're dictating where all of the money goes in society to a fine degree. Variations of this have been tried. The members of that society do not find themselves more well off.