I'm talking about the developer having to worry about scaling and not the software. This article is about how the author got a sudden influx of traffic and did not have to worry about scaling anything to support it. That influx of traffic was to his website and then to the various distribution channels of his app. There is a reality that his website would fall over from the traffic and he would have to worry about scaling it, but in this reality he is paying someone else to handle scaling it for him.
If it wasn't local first software and he paid someone else for the backend, he also wouldn't have to worry about scaling the backend. My comment is pointing out that the dichotomy isn't between local first and non local first software, but between self hosting and not self hosting.