Hmm it seems that most evidence surrounding fiber is associative. For me, although anecdotal, I think one can be healthy by avoiding caloric overconsumption and processed sugars and fats/oils, regardless of fibers. I also think it makes sense that fiber is associated with good overall health since avoiding processed food generally comes with more fiber. But of course, I could be wrong about this.

Oh, and thank you for the citation haha. :))