It’s not a circular argument, it’s a fact of how we learn things. If you’d been brought up in a world that considered base 60 to be the norm you’d be as good with that as you are with base 10 in our world, and you’d consider base 10 to be as foreign a concept as you now consider base 60.
The why, where and what for is very simple. They based their number system on being able to divide up objects more easily. Pick an object, any object, doesn’t matter, it’s easier to divide that object into equal portions if it is measured as 60 whatevers than if it is measured as 10, even if it’s the same actual quantity. 60 NewMeasurements of land is mathematically easier to divide equally among 3, or 4, or 6 or 8 people than 10 acres of land. They built that thinking right into the society with their numbering. They built their numbering system on usability during calculation, as opposed to base 10 which is built on usability during counting.
Ok you win.