Language expressiveness is more about making the interface support more use case while still being as concise. And Ruby is really good at this, better than most languages.
I suppose we have to define expressiveness (conciseness, abstraction power, readability, flexibility?), because Ruby, for example, has human-readable expressiveness, Common Lisp has programmable expressiveness, and Forth has low-level expressiveness, so they all have some form of expressiveness.
I think Ruby, Crystal, Rebol 3, and even Nim and Lua have a similar form or type of expressiveness.
If you say that expressivity is the ability to implement a program in less lines of code then Ruby is more expressive than most but less than for example Clojure. Well written Clojure can be incredibly expressive. However, you can argue that for most people it's going to be less readable than a comparable Ruby program.
It's hard to talk about these qualities as there's a fair amount of subjectivity involved.
But yeah, you are right, there is too much subjectivity involved in all of this. :)
Anyways, I hope you know I did not mean to use any of my comments against you, I was just wondering.
It's an interesting conversation.