Because he says things that are true and less well known than they should be, and then gives a clearly written argument that shows you that they are true using logic and empirical evidence.
I don't disagree with you, but other people write on these topics more compellingly, and do not include off-putting Wolfram/Doctorow-style self regard. I chalk it up to his being astoundingly prolific.
These two things can be true at once: Intelligent good people with good taste and good will find an author's writing compelling, interesting and valuable. Simultaneously, other intelligent good people with good taste and good will do not. It happens. Neither are wrong.
So far that just describes any good science paper or math textbook; the difference is that he's writing about questions of great interest to HN, like in this case "how to build a web service", "how to do software version tracking" (https://danluu.com/monorepo/), "how to do statistics" (https://danluu.com/linear-hammer/), "why hardware development is hard" (https://danluu.com/why-hardware-development-is-hard/), "why everything is broken" (https://danluu.com/nothing-works/), and "how to hire talented people" (https://danluu.com/talent/). These are topics where there is an enormous amount of hot air out there on the web, but very little that is epistemologically justifiable.