In a long discussion on youtube that started with my comment (it was later deleted), in which I was objecting some points the author of the video made, on one point I responded to another person, who asked me about fruitarianism after I mentioned it:
The one thing I should to tell you here is that fruitarians are not all alike, there are not many of them (us) but they all have their unique set of reasons to follow this lifestyle. For example, my reasons developed from ethical, aesthetic and habitual considerations, many fruitarians are religiously driven (I am a lifelong atheist myself), many think that raw food is the answer to all health challenges and eat lots of fruit as a part of the diet (I am not a raw-foodie), some do not even consume seeds, and subset of this group believe that seeds are just like babies; some eat leaves, some don't, not all fruitarians are vegans, etc. The only thing I found similar among all fruitarians I know, is that the biggest part of their diet (~75%) is fruit, usually fresh, and there are some studies already made that could be used in support of such choice.
I hope it gives you some idea about the absence of uniformity in fruitarianism, and why discussing it here is not preferable. Also, I am obviously not able to speak neither for all fruitarians, nor for all vegans.