Generally this is true, but I think you are being dismissive by throwing this truism at his note taking attempt. The point of keeping a personal wiki, is tonote the things that has come to his attention and not to forget it and to come back to it later. Writing things down gives it a concrete form. Sometime I even force myself to write down things that I read and that is a reasonable cure for my binge reading procrastination. Even if you think it as just a glorified bookmark manager, it is more useful than your browser's bookmark manager . Many people who do not maintain a wiki may not realise that knowledge is incrementally gained and by having a wiki (or any place really) to note these things makes the process transparent and recallable.

A vast superficial knowledge, along with a good memory, the ability of making meaningful connections between far away domains is a scarcely distributed skillset and a quite valuable one in today's Western world.

Note that a wider knowledge base can lead to a deeper understanding simply by having more possible connections between ideas. Our brains love connecting the dots.

Not true. So if you are a JS developer who knows React and Vue you could learn Angular (same kind of thing) or learn Haskell (different) or Systems programming (different), and I assert the latter two things would deepen your knowledge of JS more than learning the library because they allow you to see JS through another lens.

Yes, but on the other side there is a chance to gain knowledge on a higher level, because of comparing different things and finding the common patterns. But this only really works well when those things are similar enough to have common patterns.

And from experience I think it's true that at some point one should move from being a jack of all trades to become a master of some things. But as big as the world has become today, the road to this has become even longer. I think today it's not so unusual anymore to search some years or longer for your calling to master.

However wordly wisdom can help you gain better models to process reality through.

https://old.ycombinator.com/munger.html

Knowing a little about a lot of things allows you to generalize over them and learn new things faster.

For example, if you have dabbled in C++, Java and Python you are better placed to learn a new language than if you have exclusively used one of them. Even if your knowledge of that goes way deeper.

is that a good thing or a bad thing?