Storeys guide is kind of meh.
Rabbits CAN get worms, mites, etc, and that's one reason why people don't like using bedding and ground. I use bedding and have gotten mites (easy to treat). I've never had worms (harder to treat). And that's true you can get both being on ground.
But like all animals there's kind of a trade off. Storeys guide is very much American CAFO Agriculture Techniques. It's not focused on welfare/holistics much. Rabbits on the ground are much more active, they get a lot more exercise, they express a lot more natural behavior. And if you've got a secure pen that's unlikely to get parasites into the soil because wild animals can't get into it as easily. But the risk is still there and very real.
So it's about whether the risk of illness outweighs the potential for happier regular rabbit behavior in your own setup. Like if your goal is meat animals, a parasite load could be REALLY detrimental and treating that many rabbits is expensive. But the risk of an occasional parasite load in a pet rabbit might not outweigh its happiness and treating 1-2 rabbits is much cheaper/easier than a whole herd.