In order to do that you have to go the Silk Road route, and try to host the site untraceably, paying for the server in Bitcoin, with the server hosted in a country with a no-extradition policy but has fast Internet. Otherwise for the platform to exist on the "regular" Internet, with servers and server admin living in a country with laws, the platform has to start policing content - banning the sale of drugs, weapons, and murder-for-hire, along with censoring other material - porn, gore, child pornography, copyright infringing material, files that are covered under ITAR.

The Internet is rife with censorship. It just offends our first amendment sensibilities to call it that for some very specific categories.