I am not implying in any way that self-taught developers are unable of anything. I know a lot of great self-taught developers. However, many developers without formal CS training learn one or two technologies (e.g. ruby or another web framework) and believe this is enough; they even call themselves "hackers". That last approach surprised me.
I think the same applies for everyone, you have to expand your horizons unless the company you work for is extremely locked down on technologies.
Everyone should know a few languages so they have the tools they need to do their job properly, would we use a chainsaw to screw something to a wall just because we hadn't learned how to use a screwdriver yet?
