Every site-blocking proposal runs into the same problem: blocking is easy to specify and hard to aim. You order ISPs to block a domain, the site moves to another domain, and the list grows. Going after the tools people use to get around the list is the obvious next step, which is exactly why it's worrying.

Pedantic, but the mechanism matters here. 'Blocking' can mean a DNS resolver refusing to answer, an ISP dropping traffic to an IP address, or something deeper in the network.

DNS blocking is bypassed by changing your resolver in settings. IP blocking takes out every unrelated site that happens to share the address. Neither is precise.

Right, and shared hosting is the bit people forget. One IP can sit in front of thousands of sites. You don't get to block only the bad one.