Why is there so much emphasis on wealth disparity when there's substantial evidence that life is significantly getting better for the poor regardless of this di

Why is there so much emphasis on wealth disparity when there's substantial evidence that life is significantly getting better for the poor regardless of this disparity? This is just one example off the top of my news queue: https://www.economist.com/united-states/2019/05/18/american-life-is-improving-for-the-lowest-paid https://www.economist.com/united-states/2019/05/18/american-... The phrase "A rising tide lifts all ships" gets routinely mocked, but the data seems to indicate that is is true. While inequality has risen over the past several decades, quality of life even for the poorest quartile has improved.