I think good documentation, both authoritative but also that created by active users from blogs and also Stackoverflow are what make people productive in a language and enables both newcomers and experts to progress. And of course libraries and tools are being developed, which also facilitate usage. Look for example at R, much earlier than Python it had various libraries with machine learning algorithms, at the same time the language is really "unusual", so people rather rewrote libraries from scratch in Python. At least for time series analysis I think even today there are more advanced libraries available in R. But the documentation at least some years ago was just not on par with the difficulty/unconventional ways to do things. (Despite having a super helpful tightly knit community as far as I can tell) The Python equivalents on the other hand have often more documentation than needed.
I think also JS won a lot due to good documentation, in fact there used to be an SEO campaign to boost MDN docs because the JS docs used to be so bad making people write bad code, I think the language's reputation still didn't recover from that.
I think also JS won a lot due to good documentation, in fact there used to be an SEO campaign to boost MDN docs because the JS docs used to be so bad making people write bad code, I think the language's reputation still didn't recover from that.