It's a philosophical difference. As someone running a market where buyers and sellers meet I think it's valid to let the buyers and sellers participate in the exchange among themselves at their own risk. The person running the market doesn't need to treat the participants like children. Plus, if you're on the TOR network and buying obscure research chems using crypto in the early 2010s I think it's safe to assume you're more sophisticated and aware of what you're getting into than the average person.