As I said, its not the purchasing thats the biggest problem (although online purchasing does require an address - which is also risk for dark market purchases today) , however its the selling that becomes the bigger issue.  To sell to public you need to be visible to public.  If its criminal to advertise goods in exchange for Monero then there is no viable use case for monero as a currecny to pay for goods and services such as food, and utilitys, which is also where most peoples money is spent.