I feel like PbtA fits with contemporary thinking on information architectures, that avoid complex systems and entanglements across entities formed by rules. Something like a microservices architecture: each move does one job.
I can ask if the current set of rules meets all of my requirements? That is the kind of test my dwarf wizard example represents. If my requirements include a dwarf wizard and the current set of rules doesn't support it, then the set is incomplete as measured against my requirements.
One way to achieve completeness would be to limit my requirements. But TTRPGs like DW are open-ended: I feel able to enumerate requirements endlessly. Thus no finite TTRPG text can be complete by this measure. And describing a procedure for completion does not make it complete. That's what the rough beast slouching in alludes to. GM-fiat can be used as one such procedure.
Above I wrote
So this is a different test of completeness. Above I gave the example of deciding how much is "a lot" in the Ritual move. In this case, it's incomplete because a game parameter is left undefined. It's not that there isn't a move doing the job of Ritual, it's that the move itself is incomplete.
To me, this shows why I should feel comfortable with incompleteness. I agree with your extensible framework characterisation, and that doesn't make Ritual complete. Rather it is the
incompleteness of Ritual that gives it versatility.
I would again say that it shows incompleteness is an
advantage in TTRPG rules so long as
- What is afforded by the rules meets my highest priority requirements, and
- I have a satisfactory procedure for updating the rules to meet any new requirements
I can like the DW procedure and dislike that in Pathfinder. That doesn't make DW complete and Pathfinder incomplete, but it does mean that if using the latter I have no procedure that satisfies me for sustaining completeness against requirements.