The distinction here is that the links you've posted are from the browser console line, while the tool in question can take screenshots from the terminal/command line (sans browser, can be automated).
Firefox and Chrome, and most major browsers can indeed take screenshots from the browser _console_, but taking screenshots from the command line is a separate, interesting concept.
Firefox and Chrome, and most major browsers can indeed take screenshots from the browser _console_, but taking screenshots from the command line is a separate, interesting concept.