Similar thing for Ruby: it wasn't popular until Ruby on Rails. It may be just
that most programmers need to write dynamic websites, as opposed to network
services (most likely with custom protocols).
Programmers writing dynamic websites are likely to post questions on Stack Overflow. Questions on Stack Overflow create mindshare, mindshare attracts more serious programmers who can improve the ecosystem by writing generic network services. Language prospers, cycle repeats.
JavaScript is the most popular language on Stack Overflow and React is the fastest growing technology.
Without the dynamic website programmers the cycle short circuits and you end up with a terrible "new user experience" from lack of answered beginner questions and lack of interest building on the non-existent ecosystem.
