My original
website hostings didn't use CSS. I've taken over one that does and implemented CSS on another. i'm not convinced.
My
website hostings have to be compatible with browsers that don't support CSS ao the HTML has to stand on its own. There is little that can usefully be added with CSS. Using position:absolute for layout is obviously ruled out. Tables for layout may be deprecated but they work.
The biggest fault with many
website hostings is setting background colours in html and foreground (text) colours in css, or vice-versa, with the result that you get zero contrast between the text and background. In other words the
website hosting is unreadable on some browsers.
As for maintaining the
website hosting I can't see the advantage of CSS. True, you can change a style and it affects all the pages using that style, but on the other hand that means you have to check through the whole
website hosting for unintended consequences. When you're updating a single page you need to check all the style sheets to see what styles are available or whether you need to create new ones. With plain html you just do what you want to do on that page and you can test it in isolation.