And to summarize the answer of the original question to future readers. The point of properties is:
a) to help humans to better understand Wikidata
b) to help programmers (also humans :P) build the software running it
c) to make a distinction between concepts found in the world and the concepts that have been "interiorized" by the community
There might be more, but those are the main points that suggest that it is better to keep properties and items separate even if their essence is the same.