I strongly believe one can't understand this method and the sheer amount of effort necessary to consistently tend to this system and keep it alive (like Luhmann) did without the deep explanations and also at least diving into the examples of Luhmann's zettelkasten as it is digitalized.

Nonetheless - I also do not believe, that a lot of people would benefit from the zettelkasten system. It has in my opinion a very narrow target group that would massively benefit from this method, while for others it would only be a lot of work with limited benefit.

Luhmann profited from his lifelong work on the Zettelkasten (he was an avid reader and did extracts long before his university career). But once he started his university career he was able to produce on such a deep level and with such a high frequency, because he had up front invested massive amounts of time into this system.

So if one is looking for a productivity tool, I am not sure that zettelkasten is the right tool in one's belt. It needs massive investment up front and pays interest only later.

I personally look at this method (and others) as means to help keeping track of discoveries and knowledge in general. I believe that it is useful for all knowledge workers, but especially for academics & content creators.

Looks to me only good for academics who can discover new things from old texts. Not sure how it help Stem research.