Actually no. It can be that but the idea is that you should talk to someone who isn't involved with what you are doing and one of two things happen, you have a lightbulb moment like you are talking about which you can be talking with the wall at that point, or the person you are talking to is supposed to see the blatantly obvious thing you are missing and then they tell you about it. It is called Rubber Ducking because one of the guys carried around a rubber duck when developing stuff and he couldn't easily get another person to stand there and listen to him whinge on about what he was doing. It is still better to have a thinking person there but you can't always have what you want.