I don't really consider gearing efficiency to be intuitive, especially when there are so many more gears available nowadays. Also, big name bike manufacturers using available cassettes to meet a price point rather than maximizing useful gearing is bound to lead to redundancies, and that's kind of complex to grasp if you don't spend a lot of time thinking about production for various riding types. If you don't want to explain, nobody's forcing you. It's kind of interesting specialized knowledge, though, isn't it?