I don't get how this sentiment still persists. This is simply not true if you're working on more serious websites for clients who actually audit for accessibil

I don't get how this sentiment still persists. This is simply not true if you're working on more serious websites for clients who actually audit for accessibility or responsive design, nor if you want it to be maintainable by web devs that actually know what they're doing. CSS definitely isn't as messy some C++ still out there in the wild. If you're doing it right you should be able to quickly write a minimal amount of code that does what you want even for fairly large websites. Involving AI for something so trivial would just get in the way. Bad CSS is usually due to the requirements specifying a terrible design, much like how bad requirements drive bad code in any other language.