I would add that FCC doesn’t “require” use of any of these other resources, but they certainly don’t hurt as long as they’re not used as an excuse for procrastination, which is a phenomenon that Alexander Kallaway wrote about this week on Medium.
I personally used these resources here and there when I was learning (along with a lot of programming books and MOOCs) and found them helpful. Some of these (Code School, Codecademy) were part of FCC’s curriculum early on.