I'm an emt with a few other certs and training, and work for an emergency medical team in my county. For me, on the Internet I feel comfortable talking about typical exercise related health issues but there's a line when you get to diagnosing that I wouldn't cross.

Personally I worry about medical liability as would anyone with any sort of official medical training, which are the very people you'd want commenting the most. So the bulk of the respondents to health questions will end up being the least trained. I can't imagine a physician or nurse tossing around medical advice because it really does open them up to malpractice. Their medical license is how they put food on the fridge and pay the mortgage so they're understandably gun shy. Another aspect is that (if they've been working long enough) they've made mistakes which have costs people their lives and that breeds in a lot of humility or at least a desire to only make decisions when you need to and you have enough information to effectively do so.

I can talk about what I know, but even [an answer I gave to some guy about DOMS][1] (that I still believe to be right) to me crosses the line of me saying "I took your signs and symptoms and told you your medical condition."

As maddening as the constant "go to the doctor" drum beat is, unpacking that a little more "go to the doctor" means:

 - Talk to someone (doctor, nurse practitioner, etc) who is licensed to *practice* medicine. 
 - Be in a setting where they can review your medical history, allergies, signs (vitals included), symptoms, and have ready access to things like blood analysis and imaging. 
 - Be in a care setting where you can be quickly routed to a different practitioner. 

Back to my DOMS answer, I've never diagnosed [exertional rhabdomyolysis][2] or even seen a patient with it so really who I am to tell that guy what he has DOMS when exertional rhabdomyolysis can result in full renal failure? I nearly cost a guy his foot one time when I waited too long to traction him and relieve pressure on a neurovascular bundle (multiple compound fractures in the ankle and gross deformity). It was luck, not skill, that saved him from a life with one foot and that lessons got cored into my head. 

So I'm not sure what the answer is on here. I just now that I'm not an expert and I feel that people with more knowledge and capability than me would be even less prone to providing medical advice without the tools and time they need to do it properly. The cost of screwing up is just way too high. 

Edit / Follow Up:

Maybe it's the Internet culture, where we can stream in 4k, read tweets from the president in real time, and get a date in 5 minutes via tinder when "go to the doctor" just seems like such an archaic and non-modern way of doing things. Like if we can have amazon prime and tell some button on the fridge to order more milk why can't I go on the Internet and figure out what this rash is?

Maybe something someday will handle this, but as a really-low-on-the-rung medical provider my experience has taught me that you need people in front of you that you can touch and establish a relationship with. Anything else and I feel like the chances of harm get higher and higher.

  [1]: https://fitness.stackexchange.com/questions/19155/why-do-my-muscles-ache-the-day-after-i-lift-how-come-not-asap-after-my-workout/19157#19157
  [2]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4065559/