Possibly worth considering the source: the author coaches on a mechanism for collecting and collating information. They have a vested interest in the notion you have to do the work (instead of letting the machine do it for you); indeed, they hope you do the work using this method they coach on...

(That having been said: I've used zettelkasten myself a bit and I'd say it's worth a try. Probably not for everyone but the underlying idea of "building out an artifact to supplement your memory and understanding of what you've seen" is an intriguing approach).