Lactose intolerance is actually a very good example. The level of lactase production varies significantly among the population. Different people will find different amounts of lactose as interfering with their ADLs. There’s generally a point where too much milk or cheese will cause you to have gas and visit the bathroom within an hour. This is called clinical significance. If they don’t have enough clinical significance, it’s pointless to diagnose them with lactose intolerance.
Although I agree with the facts, binary „diagnosing“ isnt the only way to go about your life. You, your parents and your doctor can make decisions without a piece of paper. The problem here to me seems to be that „you‘re not diagnosed so you dont have it“ has been a valid strategy for too long and needs to go already. Seeing that your child (eg) shows signs of autism doesnt mean you need to put them in special everything but people are rightly pissed that they have suffered irreperable damage to their bodies for self medicating an issue that could have been mitigated if not soved, were our society able to accept imperfection and not reinforce stereotypes at every turn.
You can and should use nonmedicalized strategies for something that’s subclinical. That was my point. A disorder is a medical diagnosis.