Designers who cannot code come with lots of hidden costs - if they want to prototype a complex interaction, perhaps with some animation, they need some developer time or are using tools so complex that they may as well just learn to write the code. If they produce a design that doesn't work as well on a phone as it does in Photoshop, that's a lot of lost developer time. In my opinion, these are costs that a lot of organizations can't afford, and don't think about when they hire purely visual designers. All that talk about "you can only be an expert at one thing", while true, misses the fundamental point that designers don't need to be expert developers: they just need to be good enough to enjoy the benefits of being able to bring a design into reality (regardless of whether that code actually makes it all the way to production).