No, the conclusion that some people genuinely have problems can be reached without listening to the experiences of those who don't have problems, the testimony

No, the conclusion that some people genuinely have problems can be reached without listening to the experiences of those who don't have problems, the testimony of the people with problems is fully sufficient for that conclusion. As I explained above, even if some people genuinely don't have those problems, that is simply irrelevant if others do have them.