I would not agree with that assertion. Just off the top of my head, being familiar with both:

- context

- net/http as a full server framework, not just a request library

- net/http/pprof

- runtime/pprof

- runtime/trace

- embed

- testing as the canonical, required test framework

- net/rpc

- net/http/cgi

- net/http/fcgi

- net/http/httptest

- os/signal with integrated channel-based delivery

- sync/atomic with language-aligned memory model semantics

- runtime as a documented and supported API surface