The idea that fighters' or barbarians' job is combat so it's okay if they don't do much outside it comes up a lot, but is flimsy. Other classes can contribute fully to combat while having a lot more tools outside it. Fighters' and barbarians' combat skills just aren't good enough to justify their lack of capability outside it. It only sort of works when you compare them to rogues, who have more skills but need to rely on sneak attacks. Otherwise not really.