Hey! Thank you for the feedback!
It depends on what approach was chosen for a particular application: “thin” or “thick.” client. Sometimes, the business logic MUST be located in the backend, e.g., payment functionality. Sometimes, however, an application may have quite a rich frontend. And sometimes, this logic is duplicated on both sides. I guess a classic example is form validation rules. The Frontend may enforce these rules to give faster feedback to the user and reduce the load on the server. But the server has to implement these rules anyway since it cannot guarantee that the client did it before.
In this article, I focused on the “thick client”: that is, a client with heavy business logic. A backend was out of scope for me. But yes, absolutely, BE should follow the same, Clean, approach. Clean Architecture is universal and applicable to any software, I believe.
On the side note, BE world is much more advanced in terms of Clean Architecture. I guess that Frontend is too often seen as “UI only” with no business logic whatsoever. We focus too much on React/Vue and other libraries that help us deal with DOM, user interface, and forget that there is more than that.