In my experience, most people working with clay start off realizing that they don't know much about it. Then they reach a point where they feel they are gaining a little knowledge and skill but stuill realize they have a lot to learn. Then they "progress" to thinking that they know a lot about it. It is only much later that they then realize that they don't really know diddly in the big scale of the ceramics field. It is those in the middle ground that tend to make those kinds of sweeping statements. It is those in the last category that should be the ones to listen to.