My use of the word "honestly" in the 3rd-from-last paragraph was not fair, and I apologize. Please substitute the following: "So it is possible for moderns to have come by their romantic fantasies without explicitly undergoing anything like the hypothetical thought-process described above."
However accurate my hypothetical process is otherwise as a description of anyone's reasoning, the key point seems to be step (3), identifying calendar customs, folk rituals, and magic with explicit worship of pagan gods. Anyone who accepts this identification might find plenty of "paganism" in the past and present. Anyone who rejects it might look at the same data and find pagan origins or influences independently of explicit "paganism."