I guess RFC 7849 is just not clear to me that item #5 applies if item 3 contains more than 1 v=DMARC1 record. I say this because item 2 and 4 are identical, and to me that signifies that the items are a logical path, not a list of mandatory principals.
That said, to err on the side of common sense, makes good sense, otherwise we'd have to choose which v=DMARC1 record to honor.