I play all VNs on mute, it doesnt affect the story at all for me, i think ive only listened to 2 different things and thats because they was making music in game.
a good story, writing and decent art is what gets you immersed, way more than any music or sound effects.
Sound effects help with immersion.
But music is a totally different matter. Personal preferences play a crucial role in it.
While "bad" sound effects can end up annoying "bad" music can literally destroy any intended immersion.
Example:
If the story of the VN I play is that I end up with a girl in a club and for immersion sake some DJed up pop song is played regardless of the girls actions/dress
ANY chance of me feeling adventurous or horny is out the window.
With some anvils attached.
And some hand grenades for good measure.
In the past I quit "big" games that I enjoyed previously because some "hurry up" or "danger" music started playing that ignored the audio slider.
Sound design is a crucial part of games, so far so correct.
But also the prime suspect of why a game failed expectations as well.
With Visual Novels from amateur developers music mostly is not their main area of expertise meaning it is either mediocre at best or is shipped off to "professional" musicians who may or may not actually grasp the intent of the game.