Why do some recipes call for kneading pie/tart dough?
Recipes usually specify lightly kneading pie dough to help it hold together better (especially when fitting it into the pie dish) and to orienting the gluten and fat into flaky layers instead of crumbly crumbs.  Over kneading blends the fat and flour into a mortar/paste that  takes longer to cook through and is tough and cardboard-like.