The usage of the term 'step' here is in the pre-deployment development process sense. I think what this person is doing is converting SCSS to CSS on request, at runtime.
Web browsers can't understand SCSS natively.
To be truly extreme (performance), devs should consider tree-shaking unused CSS and JavaScript. This may require using Vite (Rolldown is in the works/Rollup) if there are no other options or it makes no sense to serve bloated resources. That's the reason, I chose Astro as I care about users, not prioritse the developers' minimalistic workflows.
I prefer Tailwind because it allows me to avoid duplicating classes (mine and vendors), which is an advantage over other approaches.
I did dogfooding in Go development.