You outline a lot of why I don't like this stuff. So many lies, or misinformation... Like the "CSS can't" stuff that, well, even at the time of your writing "yes it can!"
Variables -- we now have them native, and they're more useful since you can redefine them on the fly based on states. (useful for day/night toggles)
In fact, it's only now that they're native I'd even consider them useful, given how in LESS/SASS/SCSS they were more a crutch for people too lazy to search/replace.
Operators -- we now have calc native; though in MOST cases if you needed to use operators it was likely via a lack of understanding how to build layouts.
@use -- redundant to @import at best, stupid at worst when on deployment you should have a monolithic stylesheet anyways. If you have enough CSS to need to break it into enough separate files to "need" this functionality, you probably have too much blasted CSS in the first place.
See how most people seem to use half a megabyte of CSS in a dozen files to do the job of 48k or less in one file. I guess when you're writing ten times the code for nothing, sucker-bait nonsense like SASS actually makes sense.
Just as mixins are evidence of people not understanding how selectors work or should be used, how functions are typically used in cases where people are too stupid to understand nth-child / nth-of-type, and @error is for those who refuse to learn to use the document inspector built into most browsers.
To me all those LESS/SASS/SCSS trash is either redundant to "recent" changes in CSS (if a decade can be called "recent") or reeks of people failing to learn the most basic aspects of using CSS properly.
But hey, at least all this bloated crap, extra junk to learn, and extra steps for deployment and development is hot and trendy.
And of course it HAS to be "easier" everyone claims it is, so of course it's true. BARF!