All humans have different spectrums of cognitive abilities and emotional ranges. Some people have a base-rate of happiness that is higher than others, some people get psychologically aroused (anxious) to a higher-extent than average, some people can't keep out distracting thoughts as well, etc.
To say that this constitutes a "disorder", is debatable. I often feel like those that I know who are diagnosed with ADD are way more likely to have fixed-mindsets instead of growth-mindsets. They're way more likely to claim that they can't do something. They can't do well on standardized tests, they can't finish their paper, they can't pay attention in class, etc.
I was diagnosed with ADD in high-school after some BS questionnaire and never paid it any mind. I acknowledge that there are probably people that can focus longer than I can, with less effort, but the question I find myself asking is if ADD being diagnosed as a disorder is ultimately bad for people because it enables them to externalize their shortcomings in a way were they feel detached from them? Ultimately I find that this often deters people from working on improving themselves because they're comfortable having a scapegoat rather than showing improvement or grinding through something difficult.
I'm not just shitting on people with ADD/Depression/Anxiety or whatever, but I do question the millennial generation's tendency to pathologize everything. I don't see the benefit and I hate hearing people act like their individual struggles are the most pathological, damning, uniquely unmanageable problems ever. We all have attributes which get in the way of our success, the difference to me is people who see their struggle as something to improve upon versus those that diagnose themselves and take it as damning evidence that they CAN'T change.