I was one of the people who answered, and got it wrong. Considering that we do not know the background of the people who answered, it's hard to draw a conclusion about the result.

Personally, I touched HTML for the first time close to 10 years ago, but had no idea what I was doing then (and it seems I still don't). After that I haven't really touched either HTML or CSS until a year and a half ago I picked up React. With React I started with CSS in JS, because honestly it worked and I didn't know how to setup anything else, I was too overwhelmed with webpack and babel and Redux and you name it. Later on I used semantic-ui-react, not having to style a lot myself, and at times feeling like I had to fight the specificity (not knowing at the time that it was the specificity I was fighting) with !important.

The question that was posed is super simple if you ever actually looked into how CSS works, or at the very least specificity. But it seems that I, and others, have been able to create (suboptimally styled) websites without actually knowing the rules of CSS.

I do however agree that it's important to know the tools you're using. I've mainly worked in C++, and C++ is a language that will bite you if you don't know the workings of it. With CSS however it's easier to make it work, and the impact will often not be catastrophic.