I may have posted some links here previously. As with most things regarding nutrition... it's complicated
I was unable to find any of your links on here so if you wish to share a link, please do.
Those of us that are older need the help of fiber for proper "waste removal".
Anecdotally, I can tell you that for me, nothing comes close to the effects of dietary fibre in this regard.
Also, correlation of low fibre intake with incidence of intestinal cancer has been established.