OP isn't talking about targeting a (more) minimalist browser like lynx, but about making a terminal (CLI, or TUI) interface to their (ostensible) web application.

That is, they'd create a wrapper application (the reactor-blessed example suggests using js) that gives them access to the key components of the application and a way to test it out independent of the (eventual) design goals and dealing with browser compatibility. Really, the suggestion is that they'd focus on creating an http-based API, and use the terminal application as a way to develop/test it. It's a sound approach, as another commenter pointed out, as it forces a stronger separation between presentation and business logic.