From Scientific American:
…The most common psychiatric handbooks (DSM-5 and ICD-11) are clear on the status of their classifications: they are purely descriptive and are not based on underlying causes. Still, in practice, we say things like “he is inattentive at school because he has ADHD.” It is a circular statement: a child is inattentive because of his inattentiveness. When we say that someone has an attention deficit, we are inclined to look for the cause of the problem. But when we say someone has an attention deficit disorder, we might wrongly assume we have already found the cause. Or, in a milder version, assume the cause to be located somewhere in the (brain of the) individual.
On the surface, this may seem like a silly, innocent mistake. However, social scientists have shown time and again that this systematically places the problem with the individual and diverts our focus away from the context (e.g. family/school/work) where traits lead to problems.
One clear example is the relative age effect in ADHD. The youngest students in class get diagnosed with ADHD more often and receive more ADHD medication than their older classmates. It is the mirror image of the well-known relative age effect in professional sports, where relative maturity in young athletes is mistaken for talent. It seems that in ADHD diagnostics, relative immaturity can be mistaken for ADHD; a consequence of these children being unfairly and unfavorably compared to their older classmates.