We also have plenty of customers running in restrictive NAT environments (AWS being a common example), where direct WireGuard tunnels just aren’t always possible. In those cases, something like Peer Relays is essential for Tailscale to perform the way larger deployments expect.
So yes, it improves latency and UX for self-hosters, but it also helps us support more complex production environments without requiring folks to run and manage custom DERP infrastructure.