The article says this may only be an issue for those: "susceptible individuals with risk factors such as chronic kidney disease, gastric bypass, and antibiotic use."
Modern fruit has been genetically engineered (via selective breeding or other means) to be much more sweet than their wild counterparts, and hence contains much more sugar.
Surviving on wild fruit is probably not really that pleasant since most of them don't really taste that great.
PS: generally fruit have little protein, so you might also want to find some extra sources of protein too.