"Alignment and Size" and "Structure Layout Rules" sections repeat the same equations for AlignOf(S) and SizeOf(S) of structs and arrays. Is it necessary to repeat ourselves?

When I'm reading it, my first thought is "since the rules are spelled out in this specific section, they might be specialized, and I need to use them instead". Then I'd read the rules a few times only to conclude that these are the same equations exactly. So I find it confusing and unnecessary.