I have Tailscale set up for my home server and a public domain for internal services (to make SSL easy). The domain points to the local IP address (192.168.178.X) and mapdns to the Tailscale IP (100.78.X.X). I then configured Tailscale to search for <my domain> using the mapdns server.
Now I can resolve my local network device with the same SSL-protected domain, no matter if I'm out and about using VPN or at home.
Even if it‘s by design that you can share a page, you shouldn‘t be able to change account data should you? And it sounds like the author didn‘t share their page and it was still accessible.
Sonyflakes are generally more useful in massive scale environments as you won't run into conflicts due to the "machine-id" part (which defaults to the lower 16 bits of the private IP address).
There are more differences (128bit vs 64bit, rng vs time-based), I think they have different use cases.
To be honest for the application I didn't want to expose a database serial (otherwise you'd know you're user #100, for example) or use UUIDs, so it's less about scale and more about obscuring ids. The library is well suited for huge scale scenarios nonetheless.