I have my own knowledgebase in my own format and TBH I'd say it's one of the most valuable things I own. I don't think the second brain "marketing grumpf" is false - once you get rolling, you have a personal treasure trove of knowledge without having to dedicate every piece of info to memory.
The value of whatever style of note-taking suits your work and personal style has been well understood for centuries. All the productivity piffle has added nothing to it, though it has earned a few bucks from book sales, youtube ads, and merch.
