While I'm a generalist myself, and I can relate a bit to his advice, I really don't get this recent trend of patronizing everybody to become one man shows. There is a saying that shallow knowledge can be worse than no knowledge at all. For every generalist you need many specialists, and IMO the most important gain of acquiring side skills is being able to share a deeper understanding of other people's work. As an eff…
I can see things I never saw before because of it. I would never ever wish this upon someone (I spend hours trying to make the stupidest things work, but then realize I was going in the completely incorrect direction). It's a pain in the ass when I can't make something look exactly how I want it, but for a little bit it's fun. It's nice being able to hack at the backend for a while, get bored, switch to design, get bored, switch to new features I could implement. I'll be ready for the big challenges when they come. It'll be cool when I show some people one day and say "I made this, all by myself, everything that happened I thought of superficially (as I'm using bootstrap, and tons of back end libraries)". We always stand on the shoulders of giants.