Specifically, twelve is a superior highly composite number.[1] In plain (and probably over simplified) English, it has more factors than other numbers in a similar range.

Historically, problems of division have been harder to solve than problems of multiplication. You can observe counting systems and their radices develop in multiple civilizations to make dividing easier by providing more factors. Twelve inches to the foot. The long hundred. 360 degrees in a circle. Ancient Mesopotamian sexagesimal arithmetic.[2] The fact that 'dozen' is a word.

In the modern industrial era, we have computers (mechanical then electronic) to help with problems of division, but for most of history we didn't have those tools.

What's so special about ten? Probably that we have as many fingers, so some counting systems developed as base-10 and spread across the world for reasons that have more to do with geopolitics than utility for mathematics. Of course, you can count to twelve on your knuckles.

[1]: https://en.wikipedia.org/wiki/Superior_highly_composite_numb...

[2]: https://en.wikipedia.org/wiki/Sexagesimal

I'm surprised that people are finding the benefits of divisibility to be so hard to understand. Does using the metric system create this blind spot? I've heard of language creating blind spots in what people can easily understand and think about. I hadn't thought about mathematical things, like the metric system, also creating blind spots, but I guess it makes sense.