Why not use simple distillation to separate crude oil?

Simple distillation is not suitable for separating crude oil because it contains a complex mixture of hydrocarbons with varying boiling points. The boiling point differences in crude oil components are often too close, making it difficult to achieve effective separation. Instead, fractional distillation is used, allowing for the separation of these components at different temperatures, optimizing the extraction of valuable fractions like gasoline, diesel, and kerosene.