"scale" here, as with all conversations on HN about "scale", refers to the technology required to service a large number of users or usage.
I think you'll find there are plenty of conversations here where "scale" is used in reference to stuff like the business models of "gig economy" apps, or at what point your startup has enough scale to need an HR department, and so on and so forth.
If by scaling you mean increasing the number of page views that a given version of a web app can serve, then this is mostly true.
But things like conceptual simplicity, unit economics, codebase readability, strategy, etc. are also dimensions of scaleability. E.g. the only reason that startups can even exist at all is because large companies have a lower marginal output per employee.