In French cooking mushrooms are almost always precooked in seasoned water, as are the carved mushrooms, and then incorporated into recipes.
This method is fine for carved mushrooms since that is the only cooking they get. But to precook mushrooms for other recipes means a loss of both flavor and texture.
Therefore, you will find I sauté mushrooms in the butter at the beginning of some recipes, while in others I cook mushrooms in the wine, or simply add them to the sauce at the end of the cooking time. The result I want from the mushrooms depends upon how they will be treated. Also I do not like the wilted, slimy texture of mushrooms cooked in seasoned water.