I admit it, when I first heard that it wasn't good to say, "Good job!", I didn't get it. I didn't get it at all. What could possibly be bad about saying, "Good job!", I wondered?? Now I cringe when I hear the phrase, particularly when it's directed at my little ones.
Imagine if every time you did something ordinary the people around you said, "Good job!". You wouldn't believe it and kids don't either. As it turns out, kids are pretty smart.
Scribbled something on a piece of paper! Good job!!
Ate a bean? Good job!!
Got dressed? Good job!!
When you think about it, this stuff is pretty silly. Are there times when, "Good job!", might be appropriate? Sure, but it's far better to praise the process, not the result.