I think the point of this post is that most new programmers do not know things can be faster than their monstrous JS blob. The solution to slow requests is more servers instead of fixing the code.
Related to this: programmers who know an ORM or two but never learn SQL proper.
At my job I refactored a giant, slow, memory hungry reporting task into a single sql query. It used to take 10s of minutes to collate 1000s of datapoints. Now it takes 10s of miliseconds to collate a factor 10 more data. Never mind after I added some indexes to speed the thing up.
Knowing about the layer below the abstraction you're working at can be rather useful at times.
Notably, you did NOT decide to write your own dialect of SQL to "scratch an itch". Knowing the layer below the abstraction you're working at can be useful at times, but only in relation to understanding the context of how all the layers fit together and making effective, pragmatic decisions. Pointless rewrites are anything but. Good on you for avoiding that impulse and doing the right thing.
Besides, I'm not suggesting (or "demanding") that all articles explicitly state their target audience. Just that this one does a poor job of indicating it.
So I think it's a poor argument when the parent comment (to which I was responding) assumes an exclusive target audience: "not introductory programmers... more experienced programmers".
You could argue that one was supposed to assume that from context. However, I didn't make that assumption whilst reading, so I especially wouldn't expect "introductory programmers" to pick up on that either.