Why won't anyone post up?

Yesterday I watched the finals of the 3A girls state championship game between Mountain View and Charleston. It was a close, back-and-forth game, not determined until the final minutes. Mountain View had a 6-2 girl who could make her shots, and Charleston did not have anyone who could stop her. Three times she posted up down low, and three times she either scored or was fouled. In other words, she was eating Charleston's lunch, but evidently the MV coach had her on a diet, because he did not go with what was working - and lost the game. Over and over I see teams that have a good post player who just will not use him or her - why I do not know for the life of me. Yes, it is out of style these days, but it remains true that sometimes a good post game in unstoppable. When it is, why not use it?!