Medical discussion is hard because Internets are full of all kinds of people except of those who can give you a working medical advice. Also few people can formulate enough eloquent question as well. Last but not least reason is that some medical advices requires to break a law like "use morphine" or "syntecise that expensive drug from cheap components using some common lab glasses".
So, before going to doctor I use to download from torrents all books of those field which bothers me, that makes discussion of my problems with a doctor (offline) way more fruitful. But anyway, I also miss that kind of a platform you have describen.