This isn't really about Ruby. It's about the other things in the title. I suppose that calling out Ruby by name was necessary to make this blog post concrete, and to make it easier to relate to. The author also mentions Haskell, but that really isn't necessary to get the point across. The comparison could have been between Python (written in an OO fashion) and ML.
You can write, 'I hate X because of dynamic typing, side effects, and object-oriented programming' for many values of X. Similarly, the reasons why the author is drawn to Haskell can be applied to a large number of other languages.
Yes and no. Ruby has a particularly dynamic, side-effecty culture, even more so than Python (where monkeypatching is less encouraged, OO is less of a focus, and, not coincidentally, unit testing is far less a source of fuss and trouble). Haskell goes in for stronger isolation of side effects than OCaml does. Any given language will be at some point on the spectrum, but Ruby and Haskell are probably the extreme ends of that spectrum as far as mainstream languages go.
You can write, 'I hate X because of dynamic typing, side effects, and object-oriented programming' for many values of X. Similarly, the reasons why the author is drawn to Haskell can be applied to a large number of other languages.