I mean, if you know 2-3, say, static class-based OOP languages, other static, class-based OOP languages mostly look/work the same.
If you know 3+ languages with wildly divergent paradigms, you can probably pick up most new languages even if they don't look/work the same.
But if you know 2-3 closely related languages, one that isn't closely related to those 2-3 can be problematic.
Indeed. Not sure if you left it out on purpose, but my comment included (right after the part you quoted) the following: "(except the really different ones)", which covers exactly what you're talking about :)
I don't think most people simply "accidentally grok" or use Smalltalk, Lisp or Raku; therefore I consider most people don't have what takes to grok Ruby either.
People here are acting Ruby is anywhere on the same level of difficulty for a regular high-level OOP developer as C++ or Haskell.
I think that being able to dynamically replace behavior from almost anything at any point in your program is pretty much very different from Python, Java and C#.
The only other mainstream language with this capacity is Erlang, and Erlang is not exactly what I would call mainstream language.
I believe you're severally overestimating the impact and importance of one quirk when many developers are picking up wildly differing languages and decently successful at it all the time.
Javascript is pretty popular.
How so - Python is dynamic. Django does quote some magic (e.g defining methods on the fly etc).
Yeah, I've come across this in loads of companies too. In the end, I think those sort of companies don't understand that once you grok 2-3 languages, the rest of them mostly look/work the same (except the really different ones), and they are just looking for "code-monkeys" to program with them for a year or two.