Do I need a gravel pad beneath skids on my finished shed?
I would believe the builders over some guy any day.
Will a taller block and gravel make a difference? Sure it will but if you have good drainage it really won’t matter.
I have seen folks dig out earth and put rock down for the same reason “a guy said to” worst choice for them there soil was a high clay content so the rock pit filled and held water (yes it started to smell) a drainage system had to be added. If a simple plastic vapor barrier with the 4” blocks will do better than rock and taller blocking.