Let's say that your computer has the IP address 1.2.3.4. When you register for a DNS name, let's say bolexforsoup.com, you tell the DNS registrar to associate that name with your IP address. So later when my computer wants to communicate with your computer it asks the DNS system "what's the IP address for bolexforsoup.com?" And it tells me "1.2.3.4", which I can then use for communicating. The DNS service is not something you're running yourself, it's a service that someone else is running. That's the problem here. Your computer can be completely 100% FLOSS, you can be a master programmer who can manipulate your computer at will, but if my computer wants to talk to bolexforsoup.com the only way it can know the IP address for it is to ask DNS for it. That happens outside of your control. As we're seeing in this case with anti-piracy laws, this is something that an outside force - a government, a company, maybe even a lone malicious hacker - can interfere with if they want to stop me from reaching your computer.