Earlier quoted context omitted.
That's not correct. A quick search using Google's Ngram viewer shows that "design system" peaked in 1986, and had quite a long history before that too, starting in the 1960s. https://books.google.com/ngrams/graph?content=design+system&...
Are you sure about the meaning though? Afaik, it started to be used in the context of UX/UI starting from the book "Atomic Design". That is also the earliest reference in the Wikipedia article. Of course, there were systems in graphic design used earlier [1], but before 2016, the thing in the OP would be called "The US Web Design Patterns" or "...Language" or "...Toolkit" or "...Library", for the lack of a common ter…
It doesn't seem super relevant whether or not there is a CSS/JS framework to support a design system — that seems more like an implementation detail.