"The key to succesful education is involved parents. It's really that simple." Given that statement, and translating it from layman terms ("the key" and "really that simple") into philosophical terms (necessary and sufficient), I would say that tokenadult was fair in having that idea, that "the key" == "sufficient".
As an example: https://www.economist.com/finance-and-economics/2018/06/23/m...