Unfortunately the idea that you would just restyle the content a bit as needed and viola website is redesigned never really worked. At any point in history. I just wish you could get through a redesign without learning three new languages nowadays.
We have people with a religion of separating style from content, so they introduce the complexities necessary to do that. But because it is merely a religion, they don't actually do it in a way that makes it possible to actually change styling just through CSS.
Yeah...I've seen lots of code review arguments where one developer refuses to alter the HTML to make the styling easier (e.g. order of elements, wrapping elements in certain ways) and then the CSS styling requires all sorts of complex tricks. If Google or screen readers won't see any difference, striving to separate styling from content like that is a waste of time in my opinion and you should make compromises. People complain about e.g. Bootstrap's "text-center" and column classes as well because they're not semantic but they can save time when used appropriately.
The content/presentation dichotomy doesn't hold water in a philosophical sense either. Many text pieces (such as poems, but also modern text forms) require special presentation. But what was particularly absurd is to invent a new syntax for key/values.