Since they are likely using CSS modules or some other type of scopped CSS, it means the classes they write are human readable, but not guaranteed to be globally unique. For example, you have FooComponent and BarComponent. Both may have a button, so as a developer, you decide to make a class called 'button' for both of those components. The tooling will then create a unique CSS class name in each of those cases and replace FooComponent.button and BarComponent.button with a hash of some sort.

The best they could do to make it less obfuscated is to include the name with the hash. So the class name may look like 'fkljdkldjf9303-button'. However, the hash may change if the component changes for example, so still not super reliable from your point of view. Also, most users won't care, so they'd just be including extra page bloat to add the human readable names along-side the hash in production builds.

I'd argue that CSS modules and similar reduce many many bugs I've seen people make over the years and that it's a huge win in terms of developer speed and reduction of bugs. I highly doubt anyone made the decision explicitly to obfuscate the CSS...