> But it is inefficient to pass an array or struct; instead, we should pass pointers to these types.

I feel like the author hasn't used go much. You almost never work with arrays directly, you use slices, which CAN be efficiently passed around.

EDIT: Upon re-reading I think the author was making a point about the consistency of go, and how different types have different behavior with regards to pass-by-reference/copy. There's actually a pretty simple rule for it:

If the variable is a primitive, or defined by the user, it is passed by copy (ints, strings, structs, etc...). Everything else (compositional types like slices and maps, and others like channels) are passed by reference.

The outlier are raw arrays, but again you don't ever actually use those, so you can just ignore them.