[lawpoop]

When specifically was CSS explicitly and officially said to be for layout?

As I remember, it began as styling, and people started using it for layout, and that became the best practice, though not official. I don't recall the announcement that its design was for layout, but I wasn't keeping up on the news at that point.

And since CSS is officially said to be supporting layout, why aren't they thinking of all web use cases?

If CSS is not for layout of complex applications, what should one use in that case?