Any explicit knowledge is either part of a general, long-term understanding of the world (global knowledge), or peculiar to your own life and local environment (local knowledge). These mainly fill semantic and episodic memory, respectively. Declarative memory can hold either.
Local facts tend to be isolated from each other, and can go obsolete quickly. Natural memory with static linear notes suffices to keep track of local knowledge. Being able to quickly search the notes might help.
Global facts tend to connect to each other, and remain true and relevant for years or even lifetimes. Some propose using Zettelkasten-like external "second brains" to record, reflect on, and connect global facts, such as in Obsidian, Roam, or TiddlyWiki.
You can use a spaced repetition system (SRS, such as Anki or Memoire) to efficiently memorise large amounts of explicit knowledge.
Once you memorise facts, you can reflect on them in your brain, perhaps assisted with disposable writing. Spaced repetition also brings an incentive to connect facts. You can recall a fact more easily by rederiving it from others you already know, and spaced repetition rewards you for easily recalling things.
Try as you might to shrink the margin with better technology, recalling knowledge from within is necessarily faster and more intuitive than accessing a tool. When spaced repetition fails (as it should, up to 10% of the time), you can gracefully degrade by searching your SRS' deck of facts.
If you lose your second brain (your files get corrupted, a cloud service shuts down, etc), you forget its content, except for the bits you accidentally remember by seeing many times. If you lose your SRS, you still remember over 90% of your material, as guaranteed by the algorithm, and the obsolete parts gradually decay. A second brain is more robust to physical or chemical damage to your first brain. But if your first brain is damaged as such, you probably have higher priorities than any particular topic of global knowledge you explicitly studied.
I write for only these reasons:
Linear, isolated documents suffice for all those purposes. Once you can memorise well, a second brain becomes redundant tedium.