@Chayelle Raynox also offers a 5x magnification. The advantage over stacking would be cost, weight, and you're not losing all the light through stacked lenses. Shooting at an aperture of f/64 is already tough on light.
However, it's not a criticism of stacking lenses. There are pro's and con's to each method.
However, it's not a criticism of stacking lenses. There are pro's and con's to each method.