https://en.wikipedia.org/wiki/Niklas_Luhmann
The main reason it's so hip because Luhmann used it.
So, if your work is similar to Luhmanns and your cognitive profile is similar to Luhmans it makes perfect sense to try it out.
But I have no idea how you could test it's effectiveness in any sense that would provide results that are scientifically or statistically sane in any way.
Personally I've tried a "zettelkasten light" and I've found that I can keep my personal random research findings better organized that way - so instead of having just a page in a notebook, building an actual index of the notes as well, and linking thematically identical topics together seems to keep my thoughts better together. Been doing it only for a few months, though, need to see what I think about it in few years.