CSS rarely gets mentioned in skill assessment because it's more akin to a syntax than an actual language. Though this seems to be changing as more advanced features are added at a snails pace.

None of your examples break anything, thought they should be considered if writing something from the ground up, maintenance is another story. CSS semantics don't even make it into the bug tracker unless you have nothing to do, or your sole job is to write CSS. There is always more important things to do.

This is similar to how you can always spot a "new" web dev over how they obsess over WC3 validation. Sure it's important, but it's not that important.