Speaking of motte-and-bailey. But I actually disagree with the article's "what should you focus on". If you're a public-facing product, your focus should be on making something the user wants to use, and WILL use. And if your tech stack takes 30 seconds to boot up, that's probably not the case. However, if you spend much of your time trying eek out an extra millisecond of performance, that's also not focusing on the right thing (disclaimer: obviously if you have a successful, proven product/app already, performance gains are a good focus).
It's all about balance. Of course on HN people are going to debate microsecond optimizations, and this is perfect place to do so. But every so often, a post like this pops up as semi-rage bait, but mostly to reset some thinking. This post is simplistic, but that's what gets attention.
I think gaming is good example that illustrates a lot of this. The purpose of games is to appeal to others, and to actually get played. And there are SO many examples of very popular games built on slow, non-performant technologies because that's what the developer knew or could pick up easily. Somewhere else in this thread there is a mention of Minecraft. There are also games like Undertale, or even the most popular game last year Balatro. Those devs didn't build the games focusing on "performance", they made them focusing on playability.