My baby has intolerance & food allergies and I can say that had I introduced solids earlier we would have been in serious strife. Her system wouldn't have been able to cope with it. Not just the digestive tract problems associated with early introduction of solids, but the types of solids that we can introduce which are high in salicylates can exacerbate intolerances & allergies. Avocado & banana are often first foods but they are both super high in salicylates. So introducing them early to babies with intolerances CAN and WILL make it worse. This isn't an opinion either, this is factual. All you need to do is read books like Friendly Food from the Royal Alfred Hospital Allergy Unit & you can see how this can happen with babies.