Wheat/ gluten is the best studied, but for other foods how can you know if you might actually have an autoimmune issue like celiac disease and not an allergy?
This matters because, if one has an autoimmune disease like celiac, even if there are no noticeable symptoms (silent celiac), you must strictly avoid. Whereas the guidelines for allergies might be to eat at your tolerance level so that you can gradually desensitize.
What if, even below the threshold for symptoms one is causing harm to oneself as in the case of celiac? What if we just don’t know that yet for other foods?
For allergies there is also the possibility of outgrowing the sensitivity so it is recommended to periodically test tolerance, whereas for celiac disease you need to avoid for life.