Not everyone is working at even 1/10th Google scale. Most aren't working at that scale. The vast majority of sites and web apps can get away with a relatively minimal amount of CSS and modern CSS features in a one or a few concatenated files. For the rest of us, tools like Tailwind, SCSS, etc., are best treated as tools to help us be more efficient, and they are not necessities.
If basic CSS doesn't "scale", then it's time to stop and think about whether one is doing the right thing.
CSS stops being scalable much earlier than 1/10th Google's scale. Without rigorous practice, CSS' idiosyncrasies start getting in the way after 50 lines of it.
Not everyone is working at even 1/10th Google scale. Most aren't working at that scale. The vast majority of sites and web apps can get away with a relatively minimal amount of CSS and modern CSS features in a one or a few concatenated files. For the rest of us, tools like Tailwind, SCSS, etc., are best treated as tools to help us be more efficient, and they are not necessities.
If basic CSS doesn't "scale", then it's time to stop and think about whether one is doing the right thing.