Wheel-thrown pots were much superior to hand-formed pots. They were more regular in shape, more stable, and less prone to defects, and they were easier to mass-produce. However, they required specialized tools and expert potters to produce them at a commercially viable scale. So the decline of their production meant that the market for these items had simply dried up, and with it, an entire industry had downshifted to a more rudimentary form.