You do not need to hatch from an egg! An egg by definition is a female gamete.
And yet, that is the difference with the Argonians right?
Their "eggs" are still formed around the growing creature as it develops into fruition, and is ruptured while still inside the mother's body when ready to hatch, right...? If this is the case, how come we don't see female Argonians with egg pods attached to them?
Our eggs morph into the actual child, but the physical egg is gone.