Some legs to that initial post: nice!
A few comments have pointed out how this could hurt your findings, especially in an observational/anthropologic/enthnographic research methodology. Agreed!
I would not use these while doing generative research that is observation-based and meant to uncover unmet/under-met or unarticulated needs. But I would consider using these for aiding in evaluating concepts (product/service/message) that are a result of generative, observational research. I’m thinking here 1:1 interviews, not focus groups.
Every case is unique. The cards are mearly tools. I’m not suggesting a blanket methodology. Choose the right tool for the right job.
For the record, of course there are projects where you don’t need to ask anybody anything; you just make The Thing because 1) you are the expert, and 2) it is a truly new and an innovation.