It's a mixture of: standard library (see how quickly Go was adopted, especially when making a web project was an out of the box experience), documentation, and tooling is definitely crucial.

If I can download a language and have all these things out of the box (which Racket provides) then I probably will have less friction than someone programming in C or C++ (with 0 experience in either those or Racket mind you) who have to figure out what compiler to get, what editor / IDE to use, how to configure their IDE / editor, what magic terminal incantations to do all while I'm building websites and GUI's on Racket in a matter of minutes (from examples of course, but now I can play with those). All because Racket has: documentation, tooling and a good out of the box stack.