“Mix potato in your baked goods.”
I have never heard of that before! I’ll have to look that up. I substitute oil in baked goods (muffins or quick breads) with homemade (unsweetened) apple sauce. Use it measure for measure. Keeps things moist, but cuts the calories.
You bought flour, sugar, salt, coffee and soda at the store for cash money so anything you could grow yourself and substitute was money in your pocket.
You used potatoes in your bread, hunted for honey and tapped trees for sugar, added chicory to your coffee, made sourdough instead of using soda and swallowed hard and just bought the salt because there was nothing you could use instead of it.
You can also make a potato flour but it is a bit of a nuance to do so I just boil and mash the potatoes.
If you are making whole wheat do not bother to peel, just grate.