I think it’s grey enough that there’s a lot of avenues to getting information, insights, and identifying opportunities. To your point, Richard, I definitely believe it’s possible to come up with successful products using market research methodologies: market research can uncover under-served “white spaces”, like those you might see in areas like price point identification, or specific feature set arrangements that appeal to specific user groups.
The opportunities or white spaces that user research methodologies would identify are more around things that you can’t find out by remotely talking to users through surveys. For instance, that could be in identifying the gap between what people do, and what they say they do. Do and say are almost always different - not because people lie, but because it’s difficult or impossible for someone to describe specific step-by-step physical actions and their accompanying cues, like body language, facial expressions, or being sarcastic. Those things can tell a lot about user experience but would almost certainly be lost in a remote reporting scenario, such as a survey.
I look at user research and market research as being on a continuum of information generation. They’re different, but there’s some overlap (or at least adjacencies) in methods, and certainly in goals.