While technically true about pottery, most potters rely on commercially available glazes and clays which are made to have specific, reproducible results, based on proprietary recipes from ingredients sourced all over the world. Some of these ingredients may come from only one mine on the planet, and there have recently been several upheavals in the pottery community as these mines close or are no longer willing to sell to ceramic supply companies.
Many artists do still explore wild clay and glaze making, but it doesnโt seem the majority to me. Itโs on my list of things to learn and do.