I think that the comment that you relied to meant that it is easier for scientists to collaborate using a single language rather than many. For some domains, Python has emerged as that single language. That doesn't mean that Python is the best language.
Exactly this. To some extent the language doesn't matter - although I think Python has become especially popular thanks to being one of the easiest languages to learn and use in practice. Then you get lots of network effects - e.g. grad students learn python, and when they become supervisors they teach their students python.
You'd be hard pressed to find someone who only knows python, though. Where there is python data science there is usually also R, like smoke and fire. The syntaxes are similar enough, imo R a little simpler even.
