true learning/understanding (and intellectual depth for that matter) seems like something that (due to neurocognitive reasons) cannot possibly be achieved only through the process of reading, but is rather a function of the reader's quality of elaboration on what has been read. this inherently requires the reader's wilĺingness to invest work in the form of structured thought and cognitive effort as part of the reading process, which in turn - again due to neurocognitive reasons - for somewhat non-trivial thought and intellectual endeavors requires systematic note-taking and writing (https://www.youtube.com/watch?v=vtIzMaLkCaM). as a result, pure reading vs the reader's quality of elaboration on what they have read makes the difference between "feeling smarter" and actually "becoming smarter" as Sönke Ahrens (https://www.soenkeahrens.de/en/takesmartnotes) puts it.
I fully agree with the "Zettelgarden Philosophy" on note-taking as described in this article - it recognises the real purpose and value of personal knowledge management which is based on notes that embody personal comments, thoughts, insights and connections to other concepts/ideas rather than mere facts and summaries pulled out from articles. Though, my "tooling philosophy" differs in that I prefer to have my digital zettelkasten stored in simple text-files so that I can leverage the freedom and flexibility of text as a universal interface (grep for search/filter, git for version-control, unison for syncing across devices and operating systems, export/publishing through static site generators, etc) rather than being locked in and bound to the limitations of a monolithic tool (https://roamresearch.com/, https://obsidian.md/, https://www.notion.com/, etc) which https://zettelgarden.com/ seems to be a kind of.
> "We need tools that respect the importance of human engagement while eliminating the friction that gets in the way of thinking and creating." my tool of choice has been org-roam (https://www.orgroam.com/) - it combines the power of emacs (for powerful, efficient text-editing) and org-mode (as a way to structure content in simple text-files) and adds the very missing layer for personal knowledge management on top: a powerful cross-referencing system incl. bidirectional linking between individual notes/nodes/zettles. to me, bidirectional linking seems like a crucial feature for personal knowledge management systems (something that the WWW at its inception as a "collaborative" knowledge management system probably should have adopted, but Tim-Berners Lee opted for the much easier, rapid implementation of one-way links (see Jaron Lanier https://www.youtube.com/watch?v=cCvf2DZzKX0&t=3009s, and Ted Nelson's Xanadu Project)
at the end of the day, a tool is just a tool and only as useful as the user is capable of using it. I found the usefulness of my zettelkasten depends largely on the quality of my note-taking process, which is a learning process in itself. I found Ahrens' book and this blog post very helpful in teaching / reminding me of the real purpose and value of personal notes.