They aren't making something for the JS ecosystem: they're defining a new data serialization format built on explicitly defined input parsers (Scroll), and for one reason or another, its current implementation is in JS.
It turns out that creating a data serialization format built on explicitly defined parsers has uses beyond the ontological use cases, and there are several expressions of Scroll that are useful for technical use cases, such as Stamp for templating and ScrollSets[1] for structured data. The ScrollSets page is an excellent demonstration of how Scroll can be used to serialize data for human- and machine-consumption.
The first paragraph seems self-explanatory, and the templating language is simple enough that you can infer what it does when it runs. There's nothing about this that seems JS ecosystem specific, other than being implemented in a language that itself is implemented in javascript. I can imagine building a stamp interpreter in Python for example, it's not doing very much other than touching and catting text into files.
> Regardless if you specialize in React, Rails, Django, Next, Java, C#, or ObjectiveC, you probably use templates to start new projects.
Java, C#, or ObjectiveC devs are unlikely to want their first command at the shell to start with `npm`, or the software supply chain fiasco npm drags in.
That said, to jump in, here's a better starting point than this HN post link:
