It's always important to ask yourself what concepts you knew before you learned a new technology X. For someone who knows C++ and Java there are no new concepts in Go, so the tour of Go should suffice.
For someone who doesn't know what a function, a pointer, and a string is, there's more work to be done.
One of the reasons Go is praised for simplicity is that it only requires us to know basic concepts. You already know how to call a function and store some integers in a struct. All you need is to get used to the new syntax.
For those who like to flex their brains and learn to think in new ways, this could be a disadvantage, but for someone overwhelmed with information it's a godsend.
On the other hand, if you always limit yourself to Go then it will be harder to pick up other technologies that take advantage of concepts not featured there.
While I agree there aren't really any new concepts, I can think of two areas in Go that C++ and Java don't really prepare you for: error handling / nesting and classes. Go doesn't use exceptions or classes for anything really. Instead it's all DI/object embedding + interfaces and nested error values + context which can be more of a mind hurdle than expected since inheritance and try/catch are so common these days.