I have to say I do use a humidity dome but I've been planting right in soil. The minute I see a seed come up, I take it off. It's strictly for keeping the soil from drying out around the seed from my often too dry conditions in the tent. My success rate is much better like this.Humidity domes don't help with seedlings. They'll sprout and be accustomed to the climate they're in.
Clones, on the other hand, do benefit from humidity (although, not necessarily required) since it helps slow transpiration from the leaves until there are roots to uptake water.