MSI determines what audio features get turn on by their drivers.
Sometimes things like equalizers gets disabled because they have other "premium" equalizers in nahimic or dolby or dts or icepower. Operating 2 equalizers together would ruin your sound.
Sometimes they are lazy and they figure that since 99% of the handsets have their own physical volume knob --- they don't need to turn on the separate audio stream feature in order for you to have separate volume controls for your headphone. Lenovo doesn't treat separate audio stream as a "feature", it kind of treats it as a nuisance to give you a separate headphone volume control.