@qsort:
To give you an analogy, think of the "original" wikipedia article as the equivalent of an academic paper. It is absolutely the right level of detail for a particular audience (with references and links and even fancy language) whereas the simple wikipedia article is the equivalent of a NYT article introducing the same idea and probably going a bit deeper.
As a further analogy, if I had to learn about Covid-19, I'd likely start with NYT (no affiliation) and then move onto Nature/Science/BMJ
I just skimmed it, and it seems to me like high-school level math is more than enough to understand what the page is saying (at least superficially).
I get the idea behind simple.wikipedia.org, but more often than not it's just a dumbed down version of the main article that uses worse English (which is obvious, since it presumably has less contributors than en.wiki, but that doesn't help your average reader)