To say you prefer one over the other really says nothing when approaching it from a medical perspective. I am pretty sure marijuana would not help much with dulling the pain from having a couple of vertebra in your neck removed and replaced with titanium hardware. Marijuana may have it's uses but there are man made pills that do a hell of a job also.
I'm pretty sure he's referring to the side effects and other detrimental things caused by many of the big name pharmaceuticals. Marijuana helps for cancer patients, but can also relieve headaches and nausea. Sometimes it works well combined with other pills. Sometimes relieving pain isn't worth it when it causes other problems down the road. If I have a headache I'm not taking aspirin, I'm smoking a bowl. If my stomach is upset, instead of peptol, I'm taking a few hits. I believe that's the context he was using. When given the choice, I'll always stick with the natural remedy. You're right, it can't do everything, but it has its uses including stress relief. For me personally, I'd rather not ingest man made chemicals, many of which haven't been fully tested in relation to long term health, unless I absolutely have to. Lately I've been getting into cooking. It's much better for you than actually smoking.