I think it’s partly leftover dribble from the inane Gaia “theory” that was so strong in hippie circles. Everything natural (like bacteria in milk) is good, and you know, gut bacteria, yogurt, 's all good, right?

Combine that with “what doesn’t kill you makes you stronger” beliefs that they don’t realize come from right wing nuts and you got a perfect diarrhea inducing cocktail that we all get to pay for with our taxes and our nerves.