I've been writing CSS since the late 90s. SASS, especially nesting, makes it vastly easier to write, understand, and maintain. It's an unabashed win.

When kids tell say that CSS sucks, it's not annoying at all. Things change, people learn, and tools get better.

People questioning and improving old things is good, not annoying.

The problem is that "doing it the hard way" isn't just a matter of the original programmer having to put in "more effort". It's not just a matter of sucking it up. Needlessly esoteric code is less expressive, and therefore harder to maintain, and therefore will statistically have more bugs and have to be replaced sooner. That's the real cost. Masochistic programmers who insist on doing everything the hardest way possible, despite better available options, aren't taking the hard road for the sake of a better end product. They're making their end product objectively worse in the long run.

I didn't set out to attack CSS (I love CSS!), or even assembly for that matter. You're the one who's for some reason making this into a very weird hill to die on.

I wasn't attacking sass either, I've got large projects in production with both approaches. I was countering the point that it's 'impossible' or 'unreasonably hard' as someone else put it to write maintainable CSS code, which is absolutely ludicrous. Like I mentioned, CSS is included in more easy to maintain apps in production than almost any other language in existence. Sure, it's in a lot of code salads too, but that's beside the point, because OP's point was that Sass is somehow mandatory because software engineers can't be trusted to write clean code without it.

The original phrasing was "at scale". I'm only talking about sites with more than a dozen components and/or pages. At my job we have hundreds of components, some of which are used in hundreds of contexts, and we would have an insane time avoiding style leakage without nested selectors.