I like to see my eggs swell, change color, hatch. But if they were covered it could be harmful to keep uncovering the eggs, then covering them back up. It is a matter of choice.
I say that also so people cannot accidently spray the eggs with water-only the substrate should be misted with water. The water would likely be colder then the eggs and that could cause an effect on the embryo. I use a lid over the incubation cups so humidity is maintained just as if they were covered with moss (or dirt).
If you have had luck with burying the eggs-there is no rule that says you cannot do it that way
It is a matter of choice and experience. I have found when I covered the eggs with moss-I was more likely to do something that could damage the eggs.
Glad you like the book
Thanks! Tess