The fact of the matter is that if a visual novel's writing was good to begin with, it wouldn't require visuals. The end result is generally the opposite where the text is a supplement meant to bring your attention towards the visuals, which are most often of a "stimulating" nature so as to attract the interest of the type of people who would be interested in consuming such works instead of an actual book.
That's completely untrue though. I know this for a fact, too, because I both read books and play visual novels and I enjoy both but I get different enjoyment from each. Both are different and valuable.
Simply put, there's really nothing in book form outside of some light novels (and even those are not exactly right either) that handles storytelling in the same way. By mixing visuals and voice acting with a book-length script you just create a new thing basically and the experience is entirely unique. Being able to control how the story goes and to see a ton of bad endings and what ifs goes a long way to explaining what the personalities of chars are which in a linear medium is really hard to do in a concise way without stopping everything to go down some flashbacks or what have you.
So, to say that a script of a visual novel wouldn't stand up to that of a book is such a big "duh" thing, of course it wouldn't. Would a screenplay for a movie stand up to a book? Of course not. Cause it's meant to be a screenplay for a movie, not a book.
Same thing here, this is meant to be a visual novel, not a book. To simply imply that it's aiming to be an inferior type of book-like something else is just completely elitist and ignorant. It's trying to be what it is and just because people lack the tools to comprehend what that is and default to comparing VNs with books doesn't mean that they're actually trying to be books.
There's this assumption here that the only thing that matters about VNs is the writing or the script, when in actuality that's just true for books, VNs are about the art and audio too. You can't make them just be about the writing and ignore the other elements, they're all part of one whole, if you ignore those elements you're not really consuming the art right and if you compare it to different mediums it won't match up obviously since it's not meant to have as much animation or visuals as a manga or anime nor go into as much depth as a book. VNs reside in the liminal space between those other things.