I don't think you're aware of how medical marijuana works in these states.
You don't prescribe marijuana. You certify that the patient has a medical condition, one that is listed as a condition that may benefit from use of marijuana for managing symptoms, on a list drawn up by the state that the state agrees to. If you are signing then you may agree that marijuana may have benefit for certain symptoms. Essentially, you're stating a fact, and also agreeing with a statement. Last I knew, a medical opinion that is NOT a recommendation, is not illegal.
The only reason anyone looked at it was for glaucoma. Because yeah, it turns out it does have a pretty powerful effect on the muscles controlling the pupil and pressures. The MOA is real and it does stand up in terms of efficacy and side effect profile for use in glaucoma. Like cocaine, this is not a schedule 1 drug we are dealing with here. (Edit, I assumed because marijuana has some recognized medical uses, that it was not Schedule 1. It is still is. THC, but not the plant, was rescheduled more than once, from 1 --> 2 --> 3. Apparently it's been petitioned to be rescheduled
Removal of cannabis from Schedule I of the Controlled Substances Act - Wikipedia)
So I don't find it crazy that it also has effects on appetite and nausea, that are also very well recognized. It is a drug, it does things (Cray Logic ©), it's hardly surprising it does things. Various things.
I champion its use for anyone with cancer or other extreme conditions where appetite and nausea symptom control is not only paramount to well being but also extremely difficult to treat otherwise.
Now, outside of these recognized applications, where I've seen a ton of what I think is improvement not in the vein of the 5th vital sign, is in harm reduction.
Maybe patients I had that quit using tobacco products and even went on to quit smoking marijuana, perhaps you could argue they could have done it otherwise. Same with patients that appear to use less opioids or other substances for pain or insomnia (some problems are so ubiquitous...) Maybe people are just gonna have a vice and do a drug, and anything we do that isn't advancing some straight edge agenda where they do not use any recreational substances, is just enabling primitive coping mechanisms or some such. So maybe harm reduction is a myth.
Anyway, at the end of the day what annoys me is that people don't really know what it means to "prescribe" marijuana so they don't really understand what actual medicolegal risks exist.
They do, don't get me wrong.
And since physicians are actually doing it, all of the concerns you brought up have been addressed in one way or another. It hasn't been that difficult to manage, actually.
I'm not advocating its use for PTSD as a statement. I am not minimizing the stated risks and side effects, I've seen them.
All of this is navigable, and I imagine the docs who do, do it because it seems to work. I think there is even data behind it.