Sass, Pug, Haml, Slim, Stylus, and their friends all aim to make writing various bits of your frontend easier. And they mostly deliver on this primary promise. But they are all victims to the vagaries of open software development, and seem to have mostly fallen by the wayside. I loved using these through my career, so its with a bit of sadness that I realized I don't want to use them for new projects.
The amount of code you save grows with your codebase. It was 18% for that one, small example. In a larger codebase it can be quite a bit higher.
While I have, more or less, moved to just writing html-style templates, I do miss how easy it was to refactor something to have a different tag name. Vim and other editors do have shortcuts that make it easy to change both the opening and closing tag, but in indent based syntax, I didn’t have to worry about this. There was only one tag to change.