One of the major reasons Ruby didn't take off [outside of web] is because of the library availability. Ruby was pigeon holed by Rails while in Python I can reach for a library for pretty much any usecase and scenario from Genomics to Web.

The thing is that is an issue of community, because Ruby does have an FFI and there is really nothing stopping people from building libraries similar to how they're done in Python, calling out to C. They just didn't.