When you cite personal experience, the other person has no real way to respond. Anything they say will be answered with, "Well, YOU don't know, it isn't YOUR life." The person posting the personal experience will give their personal feelings on a subject they only partially understand... for example (and this will answer your earlier assumption) I do have a very close friend who has struggled for over fifty years with a mental illness. I can make all sorts of comments about the treatment he has received, etc., etc., but they can only be my observations, and he is only one 'subject' as it were... and my views would be, therefore, greatly subjective as a result, if I based them solely on my first-hand experience of knowing him over the years. Contrarily, in research, the subjective is set aside and hard facts are sought. There is a difference.
I can regale you with the story about a close family member who was given anti-depressants for depression. Turns out the drug was prescribed incorrectly - the problem she had been having prior to being prescribed an anti-depressant was a simple problem of drug interaction with her other prescriptions, this was immediately solved by changing one of the prescriptions (once the problem came to light).
In the meantime, though, she was on those anti-depressants for a couple of years. She had fallen and broken her hip due to dizziness caused by a higher-than-advised dose of the anti-depressant, which the doctor had recommended because the regular dose wasn't working. And sure it is true that the regular dose was not working... because the depression was caused by a drug interaction that had a very simple fix indeed.
You see, the answer was too quickly found at the first hint of depression, 'give her an anti-depressant!' when even a cursory investigation would have revealed that two of her drugs were working against each other. My obtaining and studying her records resulted in this discovery. The sheepish doctor took her off the anti-depressants, remedied the other prescriptions, and voila! She was her old self again. Well, except, of course, for the broken hip.
So there's your personal story. This was my mother. The broken hip changed her life, she never did live alone again.
Yet this story in my life does not mean, for me, that anti-depressants are never good 'because that happened to my mother', no. It was one incident alone, and therefore I would not base an opinion based on it alone, and that *is* the problem with such examples being used. It is far too easy to do just that.