Some of them do very simple things—jotting a few key references on the back page, or writing intermittently in the margin—but none of them implements any kind of consistent practice like the one described in Write about what you read to internalize texts deeply. It’s not that they’ve so deeply internalized and automatized those practices that they seem invisible: they’re just not doing those things.
They’re all expert readers, though, in their own way. They read for a purpose; they discuss what they read with others; they use what they read as part of creative projects; etc. So they’re not more effective than other readers for no reason at all.
In fact, the negation almost seems true: most note-taking fanatics seem to actually be quite ineffective thinkers. This should give one pause that it’s important to Write about what you read to internalize texts deeply! I suspect that the key issue here is “Better note-taking” misses the point; what matters is “better thinking”; such people are focused on “better note-taking.” People who write extensively about note-writing rarely have a serious context of use.
Here’s a more optimistic take. There are (and have always been) people who don’t write notes and are very effective. On the margin, writing may not help them much. But effective people are rare; most people aren’t. On the margin, writing may allow otherwise-ineffective people to join them. And we wouldn’t necessarily see this effect in the distribution of people out in the world, if e.g. writing were culturally unpopular, or if getting the benefits required special techniques/knowledge which were not widely known. I think it’s likely that this conjecture is true to some extent, but I’m not at all confident that the effect size matters.
My Twitter thread on this note: Andy Matuschak on Twitter: “One way to dream up post-book media to make reading more effective and meaningful is to systematize “expert” practices (e.g. How to Read a Book), so more people can do them, more reliably and more cheaply. But… the most erudite people I know don’t actually do those things!”