I think this is an unduly pessimistic view. It seems to me that grounded theory demonstrates that a similar logic can be extended to some other forms of qualitative research. Rigorous I have tried to identify here the sources of rigour in action research. From the perspective of some paradigms, some of its distinguishing features might be regarded as liabilities. I believe I have shown here that it is also possible to treat them as assets.
Participation can mean more informants and therefore richer data.
Involving participants as interpreters and co-researchers allows the assumptions of the researcher to be challenged. Qualitative data is to be found in conversation, in dialogue. If the appropriate climate can be developed, in the dialectic of conversation deeper understanding can emerge. Because action research is an action-oriented approach, plans are tested immediately in action. But so can assumptions be tested.