“Why? For fun.”
I love this. It doesn’t need a reason to exist. It’s interesting on its own.
That being said, can anyone think of additional interesting reasons for why this would be useful rather than the same toys over HTTP?
Simplicity / latency / efficiency - DNS typically just fires off one UDP packet (generally one IP packet & ethernet frame too) and then gets one back (hopefully) and it's done. HTTP requires the TCP 3-way connection handshake, then the out & back roundtrip for request/response, then the 4-way teardown handshake. If it's HTTPS you also need the 4-way TLS <= 1.2 handshake and close notification alert. Although QUIC or TLS 1.3 improves that a bit.
Anyway if you're using a 14.4 modem in a rusty bunker at the bottom of the sea you'll notice a substantial improvement :)
A couple decades ago I did SSH over DNS at the request of a client. It was pretty fun, worked surprisingly well. At the time, exactly zero firewalls stopped it.