If your css is a mess in 2024 (2016 really) it is all on the developer and not the language.
There's nothing wrong with those solutions and I've used those and similar plenty, but they are fragile. Those are conventions that have to be maintained and stuck with, and often for scoped style solutions you're also left with a hard dependency on a build step (BEM is an exception there). That may not be a problem at all, if you're using react you almost certainly already have a build and bundle step, but not every project is that way.
What I'd really like is more intellisense for css so I could take a css file and get sensible code complete and class suggestions for elements.
If you use the inspections, it can also make dead code removal really easy.