Humans eat according to their environment. People in colder environments with harsher conditions eat differently than a warm tropical environment. Your gut microbes adjust to what you eat. We are not living in the stone age.
If your going to say a study is bullshit than you need explain what part of the study is Bs? You must be a well educated microbiologist to call the study Bs.
There is a lot of people on this "candida" forum that have had problems/bad reactions to fruit..Each case can be different according to their own condition or their gut makeup. Candida yeast overgrowth can ferment fruit into toxic alcohols. There are many candida specialists that advise against the majority of fruit(especially high glycemic fruit).