I'm quite sure that all "those" gaskets are designed to be installed dry ('m not sure what is included in "etc").  The reasoning, as best I can tell, is not related to the sealing ability, but to the chance that some sealant could squeeze out into the oil or air system and cause problems.  Rather than worry about how much sealant to use and the skill of the installer the choice was to accept some risk of seepage to the outside.  If any of the components being installed are used I would recommend doing a simple test to verify flatness of the flanges - just put a straightedge across the flange and look for daylight.