Anytime we talk about "banning" something I prefer a very conservative approach (conservative as in let's not ban things unless we are really sure). We are constantly learning new things that upend what we used to accept as science regarding nutrition and how the human body works. I think we do ourselves a disservice sometimes by banning things that we don't understand (and sometimes we think we understand but really…
There are many possible culprits from gut bacteria to hygiene hypothesis of an overactive immune system going after anything that remotely looks the part due to having evolved in filthier environments and being evolutionary "calibrated" to be overactive by default because parasites immunosuppress.