In addition to what you said fiber is an important part of poop. An not just as stuff to push through the tract.
A important function of the liver is body detox. One way the liver does that is to package chemicals so they bind to fiber and get flushed out of the system. Lack of fiber can cause those chemicals to stick around and cause more problems.
One of the new characters from Stardew Valley Expanded mod. A lot of people love that mod. Personally I think it makes the game cluttered and lacks the charm of the base game.