It's not a binary system. The point is that it's better to make a decision knowing that your knowledge is imperfect and allowing for that than to do so thinking that your plan is perfect and that nothing could possibly go wrong.
Um... no, being right actually matters. Leaders that say, get half their men killed in a phyrric march to Russia failed, no matter how they are remembered. They did wrong. It isn't enough. Being the Best or Nothing is an attitude that will end in tears. It's only to be the best-- the most considered and thought out-- that one can be. Anyone can hare off into idiocy... that doesn't take bravery, or gumption, or if it does, it takes tools that could be used well and uses them for ill. All it takes is not knowing enough to be concerned, and thus not knowing enough to make informed decisions about what one's going into.
Action is like fire-- it's a means to an end, not an end in and of itself.