First of all, HPS is not yellow light, it’s red/orange, but mostly red. That’s why it’s used for flowering.
MH is blue light and promotes growth.
Yellow, orange or white are all the wrong spectrum for proper plant photosynthesis and can’t create carbohydrates for the plant to use, therefore, they offer very little value to growing plants and are absorbed by the plant in very small quantities, like green light is.
The violet-blue spectrum promotes chlorophyll production, photosynthesis and plant growth.
The red spectrum promotes budding and flowering.