Nesting and @layers make maintaining CSS drastically easier than it once was as well.
You can always have different files for different things but without @layers you'll bump into specificity issues. You'd also have to arrange your imports correctly or you spend countless hours on "why is this style being applied and not that one?".
It's what makes modular CSS (with cascade) actually possible.
I sometimes wish that CSS were reduced to the "good parts" and made simpler through it, but I realize that it's infeasible.
It has this maddening amount of features though, and as it needs to be backwards compatible, this amount can only grow going forward. But if you look at a well chosen subset of the whole thing, it actually is a quite nice language.