People died from starvation in the past. That doesn't mean that unlimited and unexamined calories are always good.
Similarly, treating serious bacterial infections with antibiotics is a good things. Sterile surgery is a good thing. Microbes don't know if that they are supposed to be symbiotic. Sometimes they can be both. They harmful in certain amounts or circumstances and helpful in others.
BTW, the idea that killing all microbes is bad is not really a controversial one. It's just the specifics that need to be worked out. For example, we know that sterilization an antibiotics raise the risk of harmful fungal infections (thrush, ringworm, etc). Wrestlers or other especially at risk of ringworm (for example) avoid anti-bacterial soap.
People died from starvation in the past. That doesn't mean that unlimited and unexamined calories are always good.
Similarly, treating serious bacterial infections with antibiotics is a good things. Sterile surgery is a good thing. Microbes don't know if that they are supposed to be symbiotic. Sometimes they can be both. They harmful in certain amounts or circumstances and helpful in others.
BTW, the idea that killing all microbes is bad is not really a controversial one. It's just the specifics that need to be worked out. For example, we know that sterilization an antibiotics raise the risk of harmful fungal infections (thrush, ringworm, etc). Wrestlers or other especially at risk of ringworm (for example) avoid anti-bacterial soap.