There's an extremely easy line to draw: "if you run the server, you make the rules". If you run a DNS server, you're free to refuse to carry any record you wan

There's an extremely easy line to draw: "if you run the server, you make the rules". If you run a DNS server, you're free to refuse to carry any record you want. And people are free to use or not use your DNS server, based on its policies. (There are various DNS servers that purport to block ads and malware, for instance.) If you run a blog, you can choose to not allow comments at all, or moderate them as you see fit. If someone wants to reply in a way you don't want to host, they can respond via their own blog. If you run a hosting company, you can (and should) refuse to host spammers, malware, people launching DDoS attacks, and so on. If you run an email server, you can choose to reject spam. Many interesting and desirable policies happen at the meta-level, based on that fundamental principle along with freedom of association. People will choose which servers to use based on the nature and quality of moderation; it's one of the defining aspects of a service.