Recently I started a "Starter" for Friendship Bread with some active (non wild) yeast. I thought it would be a good way to keep an active culture of yeast around in general and get some nice cake / breads too. However as i've been going though recipes paired with the starter for cakes, cookies, and muffins. I've noticed that all the leavening is coming from other means. So that becomes the crux of my question. If not for leavening, what value does a friendship bread starter provide?
I see Amish Friendship Bread recipes that create a starter with dry active yeast, but also notice that once they are active, they are kept active by feeding with flour, water, and frequently sugar. After the first addition of active yeast at the creation, no further dry active yeast is added, from what I can tell. This is a similar process to creating a sourdough, however, with sourdough, no dry active yeast is used. Anyway, over time, the starter you've created will pick up lactic acid bacteria, and perhaps other strains of yeast. The pH of the starter will become more acidic. So, in addition to leavening, the starter adds flavor to the recipe and adds acidity to your recipe. Baking soda and powder also help leavening, but might be more important here to preserve the correct level of acidity and encourage browning in the final formula. Baking soda helps keep acidity in balance, particularly when used with baking powder (one can use less soda). The proper alkalinity is also important to encourage browning.
It is there for taste.
The starter you describe is simply a kind of preferment. Since active yeast is added, and maintained overtime, I expect it will have a very strong yeasty-sourdoughy taste, much more so than other preferments made without a culture, or ones that are fermented for short times.
The bread recipes itself (the ones I found online) are for quickbreads, and the leavening comes from the chemical leaveners in them. Even if the starter would have a leavening capability (which I don't know, since I haven't handled it - it could be highly overfermented) it wouldn't be able to develop any of it in a quickbread recipe.