My issue with stuff you buy from dealers is that you have no quality control. If, god forbid, your cocodamol proved to be half Vim, you know that you could make a lot of money by suing the makers. So your weed is half oregano, privet or grass cuttings - whay you gonna do?
Not even going into the handling, storage and packaging issues. A good friend just lost several stone in a week from dysentry, having experimented with some Somali qat leaves - probably picked and handled by people without access to bathrooms and soap.
In addition, inhaling smoke of any kind isn't what your lungs were designed for.