Yeah the evidence on fiber is iffy. You can find studies supporting either position. But to your point I think fiber does help if one is eating processed foods. At least anecdotally, I found that to be the case. When I’ve done a meat only or meat heavy diet devoid of fiber that’s when I’ve had the best digestion and 0 constipation.
Discussion
Everyone should perform science experiments on themselves and stop prescribing diets for others they know nothing about 🤷🏻