So, I'll make a concession here -- I definitely don't think CSS is perfect, and two things that are not great about it is that I'm not convinced specificity is all that good and the focus on using native elements for style names is a big trap.

When I switched to using BEM, CSS immediately became like 3x easier, especially on large projects. And there's no downside to style overrides or user customization or maintainability, there's no 3rd-party library to install, it doesn't require me to write a single line of Javascript. All I've done is change how I name classes. For users, BEM-style CSS is easier to do user overrides on through custom stylesheets than the traditional CSS that uses semantic naming.

And I do think that's a big weakness of CSS and we might have set a bunch of people up for failure by teaching everyone that the "proper" way to use CSS is to write

  main section p {
    color: red;
  }

Nah, that is asking for trouble, you will end up with soup and you will have a terrible time trying to figure out what styles are applying to what elements. Instead, use

  .Article__Paragraph {
    color: red;
  }

and all of a sudden you won't hate refactoring as much and doing style debugging in the browser will be way nicer, and when you open up your dev tools you'll see component names instead of div soup, and you'll be able to instantly grep for the code you need to change for every single style alteration you make.

Not that BEM is the only way to do that kind of thing, it's just the version I tend to evangelize most commonly. But the big thing is, use stylesheets, definitely, but don't do a bunch of nested rules that are targeting native DOM elements. We shouldn't be teaching people to do that.