Great post. The author makes their point clearly and concisely - and what's more, they're absolutely right. The recommendation of this post might seem strange at first, since in some ways it contradicts some other programming heuristics. But it can make dependencies much more clear and explicit.
Though, Go and Typescript are not necessarily the best languages in which to fully embrace this idea. This is a scenario where type inference is very useful.
As other comments say, it can be a hassle to define sub-interfaces for each function, which can lead to a fair bit of duplicated text. But in a language with type-inference for function types (instead of only within-function type inference), the used interfaces can be inferred instead of explicitly written down, providing a lot of flexibility and allowing this principle to be followed in more cases.
Though, Go and Typescript are not necessarily the best languages in which to fully embrace this idea. This is a scenario where type inference is very useful.
As other comments say, it can be a hassle to define sub-interfaces for each function, which can lead to a fair bit of duplicated text. But in a language with type-inference for function types (instead of only within-function type inference), the used interfaces can be inferred instead of explicitly written down, providing a lot of flexibility and allowing this principle to be followed in more cases.