That may be stated too strongly, but the argument is in a statically typed language you go to all the trouble to provide the compiler with sufficient amounts of information, but then don't leverage that in your editor.

E.g. if you call a statically resolved function, your IDE should be able to take you to the function's definition.

Go was designed to make tooling easy, and that tooling has been written: https://github.com/nsf/gocode/blob/master/README.md

And it's pretty trivial to get Vim super integrated with go: https://github.com/fatih/vim-go/blob/master/README.md

And you consider that an IDE, right?

An Integrated Development Environment?

No, and nobody else does. There's a lot more baggage and feature check-boxes tied up in that name.

Because if it's a text editor it doesn't have all the info and functionality you have available in an IDE. Run tests for your current function, navigate to definition, manage large projects, configure builds, see test coverage, step with interactive debuggers, REPLs, vcs integration, symbolic refactorings, autocomplete, etc.

Most of this can be added to emacs too. Then it's an IDE.