I think his point is to not focus on an engine. You don't work for a studio and are just starting out, you need to get the experience and knowledge first. Sure when you're working in Starcraft 3 or Quake43262 you'll be using an engine made by someone else, but the fact that you now know how that engine works on the inside because you didn't use them when you started makes you invaluable. It's the same deal with Ruby programmers and only Rails programmers we have now.