And std::variant is now a better choice for cases like in the article above, where previously inheritance was used to represent a closed set of possible subtypes.
This is a nice illustration of the expression problem, which the article itself points out toward the end. Multiple dispatch is a language-level way to solve it. Crafting Interpreters [1] has a very approachable Java-based chapter that also covers these patterns in detail.
You need some sort of critical majority that cares about deeper aspects of whatever (over superfice) or else everyone focuses on superfice, as that's what all the public debates are about.
But lacking that, lisp could improve its syntax (did that, BTW not hard, just added some containers and a few standard infix operators, which all compile to lists).
And std::variant is now a better choice for cases like in the article above, where previously inheritance was used to represent a closed set of possible subtypes.