Oil in a diesel looks second hand after 10ks, let alone 10,000ks but servicing is still about peace of mind, some are happy to do it 5K, some 10K some not at all, it's the same argument that is made between those who use factory servicing and those who don't.
At the end of the day there is no right or wrong, any engine can last longer than 10K and very few owners in this country would put their vehicles under the "severe" conditions described in the book, even those spending every other weekend revving high in the bush is not considered severe.
If Toyota can make a modern diesel that will do 120,000ks in less than 3 years used as a farm vehicle and a highway cruiser without ever being serviced (not something I recommend but have witnessed on 2 occasions now) Nav engines will be fine for 10K.