The skills are critical for any front-end designer, not just the ones in startups. Companies that embrace skilled designers as their culture compete much better than others.
When I could link the book's website, I did it.
While startups tend to look at results (the ones that survive), agencies tend to look at the customer, at least most of them.
I actually believe that most designers coming from an agency would be eaten alive in a startup, along with their "photoshop skills". This people don't even know what UX means, never conducted a usability test (usability = I look at the website and say what I think), and definitely don't read HN.