I don't know why someone would suggest not using personal experiences or real life examples in hubs. I wouldn't overload a hub with anecdotes, but I use them quite frequently. As you said, using examples may help to clarify a theory or idea. For example, I wrote a hub about the causes, symptoms, and treatment of cerebral aneurisms. I could've simply stated the facts, but I also added a section about what my mother experienced. I think her story helped the readers better understand the medical facts I presented. I say use them as long as they add to or explain your topic.