Who enables CGO just for DNS resolution? That is not a thing for a long time, you just reminded me of that. Sure, if you have some complex config instead of a simple default, you would want to use libc and getaddrinfo, that is on you. What other issues are there? Go simple uses the network protocol for DNS, and it reads just resolve.conf; it does not care about LDAP or NSS or whatever there is.
> if you have some complex config instead of a simple default
Yup, exactly that. You don't always control the environment in which your software is going to run...