@Nocta@octodon.social because of its age, it's the result of a time where you could leave your dice in the sun or the oven and they would become squashed, it was also a verrry common defect depending on who you asked (IIRC part of Lou Zocchi's sales pitch was how his dice were rounder than other makes). Opposite-face balancing is sufficient for those dice. But also it is just really tedious to search for fully balanced layouts (or even discover they exist at all). I had the advantage of a modern computer.
@Sophie@dice.camp@Nocta@octodon.social and after a while, I think it just became iconic in its own right. A particularly experienced dm will be able to tell you what you rolled even if the number is faded, so long as the surrounding numbers are visible.