I'm sorry to hear about the struggles this has put you through, but I might mention that it is not universal that diagnosed sufferers of ADHD are unable to engage with their interests. In fact often direct interests can be highly engaging, while things that need to be done but are not interesting are debilitatingly difficult (executive dysfunction).
As with ASD and neurodivergency at large, ADHD is a spectrum, with differing impacts for differing people.
Could not disagree more. Nothing is “interesting” in perpetuity. Hence why so many with ADHD engage with various topics in an intense but sporadic manner.
In the overwhelming majority of cases this scattershot approach is deeply frustrating for the individual, and orders of magnitude less productive - in terms of meaningful creation and innovation - than persevering on a focused set of tasks.
I don’t think your comments are in conflict, being engaged with an interest does not necessarily mean being directly engaged with a project/task related to that interest. I definitely empathize with the scattershot approach being frustrating, but i think that comes out of an intense interest in a topic, and a lack of ability to focus on a specific task, even if it is self-selected and related to an interest.
I can think of many examples of times where I was unable to complete a project (in part) due to a drive to answer every question that I encountered in the process, and questions branching from those answers. So yes it does definitely impact productivity and perseverance for specific tasks, but I would separate that from the unique ability to learn intensely about interesting topics with reasonable depth and exceptional breadth that ADHD seems to give.
As with ASD and neurodivergency at large, ADHD is a spectrum, with differing impacts for differing people.