A language feature isn't a moving part. I would say that what makes a language "powerful" is the capacity to express complex concepts simply.

CSS and HTML are not a languages built for expressing complex concepts at all

I think you’re familiar with metaphors and that this is a display of obstinacy.

"Moving parts" is a metaphor for pieces of a system that add operational complexity, and it's not a useful metaphor in this case because a language just having some feature doesn't add any operational complexity

Well, I have to disagree, and I'm not alone on that.

This is the entire premise of Douglas Crockford's book, JavaScript: The Good Parts.

Friction and wear?

KISS.