Comment by csande17

> black has more contrast by either measure

No it doesn't? The screenshot of the calculator in the blog post very clearly shows that white has a greater contrast according to APCA. (If the negative numbers are confusing, you can also put the colors into a BridgePCA calculator like https://www.color-contrast.dev/?txtColor=FFFFFF&bgColor=317C... to see WCAG-2-style "contrast ratio" metrics computed using APCA.)

The point of APCA is to make the contrast calculation more perceptually accurate, not just lower the threshold.