The general idea is that you can do some pretty interesting things with DNS records beyond domain name lookup and verification.
Typically one sets up their handshake node with a DNS resolver to serve records, so in theory, if everyone used handshake node ups for DNS, this could be uncensorable
Which reminds me of a story. At Google in the mid-2000s, we used a corporate version of Google Chat, embedded in Gmail, much as it is today. One key difference in the UI was that your status appeared as text right below your name in other people's contact lists. Your status could be active, idle, away, or any freeform text that you set it to. The status lines in the contacts list updated in real time (ordinary today but remarkable back then). So people figured out that they could have an odd kind of one-to-many chat conversation by frequently updating their statuses. Not everyone was in everyone else's contacts list, so it was actually one-to-who-knows-how-many. And people used it accordingly, as if they were shouting stuff in a large room -- "does anyone know what's for lunch today?" "I heard it's lasagna" "beef or vegetarian?" etc.
Anyway, Evan Williams worked at Google back then, and I assume he saw these ephemeral messages flickering across his screen, same as I did. I wonder whether that planted the seed for Twitter.
I wanted to mention Carmack's .plan but I thought it's too old for blockchain...