I assume it was first as anti-scraping / anti-adblock measures but then frameworks with styled components spread it even further.

Remember when the trend was "semantic class names" and folk would bikeshed the most meaningful easy to understand naming schemes?

How we have fallen.

I was doing my most intense period of frontend work during that era. I went to work on backend for a long while and came out of my cave into this bullshit. This is worse than Struts, which was a bad trip we all eventually woke up from.