This post doesn't cover why someone would want to do this. If this is to reduce file size, using JPEG (or more modern AVIF or JPEG XL) directly will likely prod

This post doesn't cover why someone would want to do this. If this is to reduce file size, using JPEG (or more modern AVIF or JPEG XL) directly will likely produce better looking images at smaller sizes. However, for lossless image compression, like PNG or GIF, reducing colors might be worth doing.