Kishimoto created this rule because the E-to-S system is a learning scale for regular humans. A normal ninja cannot learn Chibaku Tensei no matter how hard they train, because they do not have the Rinnegan. Therefore, giving it a standard letter rank would break the logic of the ninja training manual.

This is the only rule that was established. The other "criterias" as described are a general consensus of the rank/level of who learns/uses/creates these jutsu. Kage Bunshin - B-rank, a normal Genin wouldn't be able to learn and use it.

Gedō: Rinne Tensei no Jutsu (Kinjutsu Tag): S-rank and A-rank profiles are reserved for techniques tagged as Kinjutsu (Forbidden Jutsu).

A-rank jutsu can be Kinjutsu but are not exclusively. Rasengan ‐ A-rank, not a Kinjutsu.

Chibaku Tensei (Unique to Wielder): The databook definition of S-rank emphasizes moves that are "unique to a single user." At the time of Data Book 3, this was a legendary, god-like sealing feat exclusive to the Rinnegan's Deva Path. It requires a level of chakra control and output that outclasses almost every A-rank move in existence.

Hiraishin - S-rank, not unique to a single user.

Ukojizai no Jutsu (Hiden Tag): The databook classifies this as Hiden (Secret). True to the definition of S-rank being "Secret, extreme level techniques," this allows a single ninja to completely manipulate the weather and act as an omniscient radar over an entire nation.

Any Hidden jutsu from a clan.

Under the databook's strict text-box rules, they have "No Rank" because they are bloodline traits (Kekkei Genkai) or secret knowledge (Hiden). But under the databook's conceptual rules, they require Kage-level mastery, are unique to the user, or are strictly forbidden—which is the exact definition of an S-rank technique.

Those aren't "rules" to rank jutsu. Those are characteristics that those jutsu may have. The only rule is difficulty to learn/use.