I disagree. The law in most countries already allows for prosecution for services that exist primarily/solely to aid in the commission of crimes. For example, torrent websites are periodically taken down and seized based on laws around conspiracy to commit copyright infringement.

Therefore, the law already allows websites or services to be shut down if their primary purpose is to enable illegal behavior. The Silk Road is a perfect example of this. They were basically and eBay for drugs and other things. While they didn't actually possess or sell the drugs themselves, no one anywhere considered the site to be legal.