The internet, phones, email, regular mail, roads, electricity, software and on on have predominantly good and productive uses. File sharing websites attract percentage wise more bad than good, at least more bad than what I'm comfortable with.
So in the end that's a moral call and in this case my decision was to shut it down because of the types of crimes involved and the number of criminals on the service totally outnumbered the 'good guys' and our ability to deal with the assholes was limited.
I guess we should all stop using cash, then?
As for how it is possible for all of the available currency to be contaminated with traces of drugs and yet that this does not need to prove that all (or even a majority) of the cash transactions done are drug related, I'm sure you're smart enough to figure that one out for yourself, but evidence such as this will figure prominently in the kind of discussion that will visit us some years into the future.
There are free file upload services and there are ways to upload from command line(1).