Ruby is too forgiving, has multiple syntaxes for the same thing, and lets people do really obscure shit in a large codebase (monkey patching, hidden imports, etc). In short: it enables developer laziness.
I've found Ruby code the hardest to debug over the years. Also, I think the web development community is waking up to the value of type safety.
I will use Ruby for the occasional script because I like its backtick syntax for invoking other commands, but that's it.