Hostname discovery (mdns), etc solves it on local networks.
If DNS is down or broken, it would be difficult for me to "use the internet", and I'd have to copy and paste a lot anyways.
mDNS is slow and unreliable and on large networks it doesn't scale. I personally don't find it very useful since half the time it barely works even on wired LANs let alone big WiFi or distributed networks. It's also prone to naming conflicts (is this linux-1, linux-2, or linux-3?) and other OS configuration issues and is not secure.
