Wikipedia says:

A "disease" or "medical condition" is an abnormal condition of an organism that impairs bodily functions, associated with specific symptoms and signs.

The key word is abnormal. If something is naturally common in humans, and doesn't impair any bodily functions, it shouldn't really count as a "disease". Like being short, as a matter of fact.

FDA has these views, as they only approve treatment of people with specific shortness-causing disorders, or within 1.2% of most extreme shortness (which is highly atypical). If people pursuing height expand this band to bottom 50% of current population, or bottom 80% of historical record, and redefine it as an illness, then it will be a lie, as a matter of fact.

Even better case is premature ejaculation, which is estimated to "affect" 30%-70% of American males. It doesn't impair any bodily functions. So it's factually incorrect to claim it's an illness.