I disagree with this.
This doesn’t apply to concepts that are focused on with the mathematics based curriculum. Math doesn’t go out of style. Regardless of language, environment, technology your using, its the same.
Furthermore, as noted in the article these topics are actually not taught very often in any platform beyond colleges. Making it “ripe” for learning. Especially as the “main weakness” of curriculum’s like freeCodeCamp is usually the lack of focus on the underlying theory. FCC already teaches a lot of practical skills, it doesn’t teach everything, but it does go over a lot. However, few online curriculum’s focus on the hard Computer Science topics underpinning a lot of what your learning.
It could be argued that “time and effort be spent on topic X, could be spent on topic Y”, but I find it really hard to say a technology, even one like TypeScript, is more important than the underlying theory. Yea your resume might look better, but understanding theory is what makes you be able to do your job better.