None of these requires SCSS at all. You may verify by grabbing the SCSS they provide in the codepen and pasting it into http://www.sassmeister.com/

Most examples are equally compact in plain old CSS. In fact, many of them are just plain CSS displayed in a window labeled "SCSS".

The places using SCSS seem like they're simply being more sane in allowing a user to change numbers trivially. Instead of saying "just change all the 400px throughout to 500px", one can change the `$slide-width` definition in one place (usually at the top).

There's also the style preference of nesting to group. But neither of those make it a strict dependency.

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EDIT: I'm not saying that I disagree with your assertion that CSS is a bad place to layer logic from a maintainability standpoint; I'm more pointing out that blaming it on SCSS makes no sense in this context.