How? Should we ban Amazon and Ebay?
We haven't banned pawn shops, either. But we do understand that they are a conduit for theft and can induce other crime, and so we tend to impose a certain amount of regulation upon them to reduce the scope of the harm.
What exact form that would take is up for discussion.
And, of course, there's other secondary markets-- sketchy people with tables illegally selling gray market consumer goods.