Short version:
It's an absolute garbage.
A bit longer:
CSS is a good tool. CSS is enough for itself and what it is. I understand it has lack of some tools, such as nested blocks and etc. So having something such as scss or less might be reasonable, specially for $variables.
Yes, you do not need for loop in css (usually).
I see only people who never care about the actual product go this way, they try to show off and just add another layer of complication to the software, why even it is necessary to run css with javascript?!
Look at these projects final result. Garbage. Doesn't work in different devices. Doesn't animate smoothly. Because they are always busy with fixing styled components.
It has terrible performance, extra learning curve, code structure will change completely, you can't use normal css libraries such as bootstrap, then in order to address such issues, you have to add tons of more libraries to the project.
I would rather stay away this as much as possible, and advise to anyone wants to show off, they can learn some magic tricks to show to girls in a bar rather making a 2 hour work 12 hours and ruin other co-workers weekend, getting laid on is better than getting laid off.