Taste
Traditionally all of our condiments, salad dressing, cheese,
milk drinks, fruit juices were ferments. And they are all delicious. In fact they are what make food worth eating. But convincing folk to pay more for the good stuff or to prepare ferments day/weeks/month before they eat it or drive out of there way to a farmstead that does, well I think you can give info but very low immediate conversion.
Food Preservation
Before Fridge, Costa Rica to Maine 1Day shipping of foods
Health
Digestive enzymes to aid us
Pre-treatment of compounds humans don't like a whole lot (food intolerance, inflammation)
Outcompete bad microbes passively for valuable real estate in our gut and other resources
Active suppression of bad microbes by releasing compounds that irritate and kill them and eating them
Releasing compounds that make it into our blood stream that help with blood sugar, blood fat/cholesterol, mood/neurotransmitter, and our hormones.
And yes while we can get some microbes from tapwater and bad superbugs from hospital and good bugs from yogurt, they are all different microbes. And I don't think that tap water much less hospital is the best place to get the best bugs. Where I, due to recommendations by
alot of experts, suggest you get these good microbes is from milk kefir, koji/amazake, red rice, water kefir, kombucha, yogurt, etc.