why the scss file need different type of loader

Question

Now I read the config that package the scss file write like this:

{
        test: /\.css$/i,
        use: [MiniCssExtractPlugin.loader, "css-loader"],
      },
      {
        test : /\.(scss)$/ ,
        use: [
          MiniCssExtractPlugin.loader,
          {
            loader: "css-loader",
            options: {
              modules: true,
              sourceMap: true
            }
          },
          "sass-loader"
        ]
      }

why the scss file need 3 type of loader? what is the parse process? first using MiniCssExtractPlugin.loader then css-loader and finnally sass-loader? why did not using the only one sass-loader to parse the scss file?