Code that runs in goroutines looks no different from code that runs outside goroutines. You do regular blocking IO. The application code of a performant RPC / HTTP server never needs to refer to any kind of concurrency construct, unless it wants to make outbound calls in parallel. (Your HTTP or RPC library takes care of dispatching inbound requests onto goroutines).

As much as I want a more expressive language, all the explicit async/await, futures, callbacks, etc. junk needed just for your API handler to cooperate with concurrent requests (not even do its own parallel processing) keeps on sending me back to Go. I look forward to being able to write Java in the same style.