@towme yes, the majority of MySensors users use the nrf24. It is cheap and many users prefer not having to install wires to all their sensors. But, maybe more importantly, nrf24 was the first communication supported by MySensors so the combined community has much more experience with it.
All example sketches are supposed to work with any transport type (nrf24, rfm69, rs485, ...). The motion sensor example has a list where users can decide which one to use. But I see that the alternative of not enabling any of the transports might not be intuitive, so there the documentation could be improved.
We should probably also update https://www.mysensors.org/about/components#the-radio to better explain non-radio alternatives.
Big thanks for your feedback. It is feedback like this that continuously makes the documentation better.