The disorder is a problem with consciously managing attention. Hyperfocus is as much a marker for ADD as the inability to focus, as is the inability to choose to NOT think about something.
What changes it from just being interested in a bunch of different things to a disorder that requires treatment is when you find other stimulus so distracting that you are regularly unable to choose to focus on an important task or subject.
Like most of these, it is a continuum, and it is not always easy to say when something goes from personality trait to actual disorder. Mark is clearly on the spectrum, but appears ( given his continued accomplishments ) to be able to it well without the aid of a psychiatrist. I would imagine most of the boingers, given their career choices, are the same.
Most psychiatric issues exist on a continuum like that, and it isn't always easy to tell when something goes from bad habit/personality trait to a pathology.. and even when you reach the point where it is pathological, it's not always easy to tell when therapy is sufficient vs. where medication is warranted.
I suffered with an anxiety disorder for years, until I finally found a psychiatrist I adore. After working with her for a while and consulting with my therapist, she suggested I try an ADD med - and it was literally miraculous. All the ways of coping with anxiety and fearI learned in years of CBT ( cognitive behavioral therapy- get your mind out of the gutter ) started working, literally overnight.
I now take nothing but an ADD med a few days a week, and I am happier than I ever was on much stronger drugs, but I did need treatment to get me there.