As I understand it, the problem is with the temperature of the water not the humidity. If you have room temperature water or higher and you don't get enough on the eggs to seriously lower their temperature, it should be the same basic effect as having the hen take a walk and letting the eggs breathe for a minute. An egg that would hypothetically be kept in a pretty constant temperature range in the incubator would not really be kept within that range in the wild. Keep in mind that chickens raised baby chicks entirely without human interaction, even before we came along with incubators and brooders and technology.
If the eggs are mostly or completely submerged, the semipermeable shell doesn't exchange gases and the chick suffocates. If you pour cold water on the egg, the chick gets too cold and dies. Other than that, it's all pretty flexible.
Of course, keep in mind that I have never raised chicks before and am now very anxiously awaiting my first order. This is based on about 12 years of research and absolutely no life experience. The only birds I've actually known have been guineas, who are just a big ball of dumb with feathers. Seriously, if you could market stupid, guineas would be cash cows. Not exactly the hallmarks of bird intelligence. Probably chickens take much better care of their eggs.
*Edited because I apparently can't spell. I dum.