Libraries. RoR did swing some attention to Ruby, but it's not the first thing that comes up in almost any context. It almost comes up in no context at all except if people are asked what scripting language they like in general. Python comes up all the time and you probably have it installed already as it comes with the OS.
Don't understand why Ruby is so much less popular. Seems like Python is de facto "first language" (it was for me), but I would advocate for Ruby.